Embeddable: Create core dbs in proper subdirectory

140_dbs/src/gplx/core/srls/Dbmeta_dat_itm.java

@@ -13,3 +13,10 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.core.srls; import gplx.*; import gplx.core.*;
+public class Dbmeta_dat_itm {
+	public Dbmeta_dat_itm(int tid, String key, Object val) {this.Tid = tid; this.Key = key; this.Val = val;}
+	public int Tid;
+	public String Key;
+	public Object Val;
+}

140_dbs/src/gplx/core/srls/Dbmeta_dat_mgr.java

@@ -13,3 +13,16 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.core.srls; import gplx.*; import gplx.core.*;
+import gplx.dbs.*; import gplx.dbs.metas.*;
+public class Dbmeta_dat_mgr {
+	private final Ordered_hash hash = Ordered_hash_.New();
+	public Dbmeta_dat_mgr Clear() {hash.Clear(); return this;}
+	public int Len() {return hash.Count();}
+	public Dbmeta_dat_itm Get_at(int idx) {return (Dbmeta_dat_itm)hash.Get_at(idx);}
+	public Dbmeta_dat_mgr Add_int(String key, int val) {
+		Dbmeta_dat_itm itm = new Dbmeta_dat_itm(Dbmeta_fld_tid.Tid__int, key, val);
+		hash.Add(key, itm);
+		return this;
+	}
+}

140_dbs/src/gplx/core/srls/Gfo_srl_ctx.java

@@ -13,3 +13,9 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.core.srls; import gplx.*; import gplx.core.*;
+public interface Gfo_srl_ctx {
+	Gfo_srl_mgr_wtr Wtr_bgn(String key);
+	Gfo_srl_mgr_rdr Rdr_bgn(String key);
+	Dbmeta_dat_mgr Rdr_subs(String key);
+}

140_dbs/src/gplx/core/srls/Gfo_srl_itm.java

@@ -13,3 +13,9 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.core.srls; import gplx.*; import gplx.core.*;
+public interface Gfo_srl_itm {
+	Gfo_srl_itm		Make_new(Gfo_srl_ctx ctx);
+	void			Load(Gfo_srl_ctx ctx, Gfo_srl_itm owner, Gfo_srl_mgr_rdr rdr);
+	void			Save(Gfo_srl_ctx ctx, Gfo_srl_itm owner, Gfo_srl_mgr_wtr wtr);
+}

140_dbs/src/gplx/core/srls/Gfo_srl_mgr_rdr.java

@@ -13,3 +13,12 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.core.srls; import gplx.*; import gplx.core.*;
+public interface Gfo_srl_mgr_rdr {
+	void Itm_bgn(String key);
+	void Itm_end();
+	boolean			Get_bool	(String key);
+	int				Get_int		(String key);
+	String			Get_str		(String key);
+	Object			Get_subs	(Gfo_srl_ctx ctx, Gfo_srl_itm owner, Gfo_srl_itm proto, Dbmeta_dat_mgr crt_mgr);
+}

140_dbs/src/gplx/core/srls/Gfo_srl_mgr_wtr.java

@@ -13,3 +13,13 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.core.srls; import gplx.*; import gplx.core.*;
+public interface Gfo_srl_mgr_wtr {
+	int Uid_next__as_int();
+	void		Itm_bgn(String key);
+	void		Itm_end();
+	void		Set_bool	(String key, boolean val);
+	void		Set_int		(String key, int val);
+	void		Set_str		(String key, String val);
+	Object		Set_subs	(Gfo_srl_ctx ctx, Gfo_srl_itm owner, Gfo_srl_itm proto, Object subs, Dbmeta_dat_mgr crt_mgr);
+}

140_dbs/src/gplx/core/stores/DbMaprArg.java

@@ -13,3 +13,13 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.core.stores; import gplx.*; import gplx.core.*;
+public class DbMaprArg {
+	public String ObjProp() {return objProp;} private String objProp;
+	public String DbFld() {return dbFld;} private String dbFld;
+	public static DbMaprArg new_(String objProp, String dbFld) {
+		DbMaprArg rv = new DbMaprArg();
+		rv.objProp = objProp; rv.dbFld = dbFld;
+		return rv;
+	}
+}

140_dbs/src/gplx/core/stores/DbMaprItm.java

@@ -13,3 +13,38 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.core.stores; import gplx.*; import gplx.core.*;
+public class DbMaprItm {
+	public String TableName() {return tableName;} public DbMaprItm TableName_(String val) {tableName = val; return this;} private String tableName;
+	public Ordered_hash Flds() {return flds;} Ordered_hash flds = Ordered_hash_.New();
+	public Hash_adp ContextFlds() {return contextFlds;} Hash_adp contextFlds = Hash_adp_.New();
+	public Hash_adp ConstantFlds() {return constantFlds;} Hash_adp constantFlds = Hash_adp_.New();
+	public List_adp Subs() {return subs;}
+
+	public DbMaprItm Flds_add(String objProp, String dbFld) {flds.Add(objProp, DbMaprArg.new_(objProp, dbFld)); return this;}
+	public DbMaprItm ContextFlds_add(String s) {
+		DbMaprArg arg = (DbMaprArg)flds.Get_by(s);
+		contextFlds.Add(arg.ObjProp(), arg);
+		return this;
+	}
+	public DbMaprItm ConstantFlds_add(String dbFld, Object dbVal) {constantFlds.Add(dbFld, Keyval_.new_(dbFld, dbVal)); return this;}
+	public DbMaprItm Subs_add(DbMaprItm... ary) {
+		for (DbMaprItm itm : ary)
+			subs.Add(itm);
+		return this;
+	}
+	public DbMaprItm Subs_get(String find) {
+		for (Object itmObj : subs) {
+			DbMaprItm itm = (DbMaprItm)itmObj;
+			if (String_.Eq(find, itm.key)) return itm;
+		}
+		throw Err_.new_missing_key(find);
+	}
+	public DbMaprArg Flds_get(String key) {return (DbMaprArg)flds.Get_by(key);}
+	SrlObj proto; String key; List_adp subs = List_adp_.New();
+	public static DbMaprItm proto_(SrlObj proto, String key, String tableName) {
+		DbMaprItm rv = new DbMaprItm();
+		rv.proto = proto; rv.key = key; rv.tableName = tableName;
+		return rv;
+	}	DbMaprItm() {}
+}

140_dbs/src/gplx/core/stores/DbMaprMgr.java

@@ -13,3 +13,34 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.core.stores; import gplx.*; import gplx.core.*;
+public class DbMaprMgr {
+	public DbMaprArg[] RootIndexFlds() {return rootIndexFlds;} public DbMaprMgr RootIndexFlds_(DbMaprArg... val) {rootIndexFlds = val; return this;} DbMaprArg[] rootIndexFlds;
+	public DbMaprItm Root() {return root;} public DbMaprMgr Root_(DbMaprItm v) {root = v; return this;} DbMaprItm root;
+	public List_adp OwnerStack() {return ownerStack;} List_adp ownerStack = List_adp_.New();
+	public Ordered_hash ContextVars() {return contextVars;} Ordered_hash contextVars = Ordered_hash_.New();
+	public List_adp MaprStack() {return maprStack;} List_adp maprStack = List_adp_.New();
+	public void EnvStack_add(DbMaprItm mapr, SrlObj gobj) {
+		for (Object argObj : mapr.ContextFlds()) {
+			DbMaprArg arg = (DbMaprArg)argObj;
+			Object contextVal = Gfo_invk_.Invk_by_key((Gfo_invk)gobj, arg.ObjProp());
+			this.ContextVars().Add_if_dupe_use_nth(arg.DbFld(), contextVal);
+		}
+		this.OwnerStack().Add(gobj);
+		this.MaprStack().Add(mapr);
+	}
+	public void EnvStack_del(DbMaprItm mapr, SrlObj gobj) {
+		for (Object argObj : mapr.ContextFlds()) {
+			DbMaprArg arg = (DbMaprArg)argObj;
+			this.ContextVars().Del(arg.DbFld());
+		}
+		List_adp_.Del_at_last(this.OwnerStack());
+		List_adp_.Del_at_last(this.MaprStack());
+	}
+	public void Clear() {
+		ownerStack.Clear();
+		contextVars.Clear();
+		maprStack.Clear();
+	}
+	public static DbMaprMgr new_() {return new DbMaprMgr();} DbMaprMgr() {}
+}

140_dbs/src/gplx/core/stores/DbMaprMgr_tst.java

@@ -13,3 +13,126 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.core.stores; import gplx.*; import gplx.core.*;
+import org.junit.*;
+import gplx.dbs.*; /*Db_conn_info*/
+public class DbMaprMgr_tst {
+	@Before public void setup() {
+		mgr = DbMaprMgr.new_().RootIndexFlds_(DbMaprArg.new_("id", "disc_id"))
+			.Root_
+			(	DbMaprItm.proto_(MockDisc.Instance, "discs", "mock_discs")
+			.	 Flds_add(MockDisc.id_idk, "disc_id").Flds_add(MockDisc.name_idk, "disc_name")
+			.	 ContextFlds_add(MockDisc.id_idk).Subs_add
+			(		DbMaprItm.proto_(MockTitle.Instance, "titles", "mock_titles")
+			.		 Flds_add(MockTitle.id_idk, "title_id").Flds_add(MockTitle.name_idk, "title_name")
+			.		 ContextFlds_add(MockTitle.id_idk).Subs_add
+			(			DbMaprItm.proto_(MockChapter.Instance, "chapters", "mock_chapters")
+			.			 Flds_add(MockChapter.id_idk, "chapter_id").Flds_add(MockChapter.name_idk, "chapter_name")
+			,			DbMaprItm.proto_(MockStream.Instance, "audios", "mock_streams")
+			.			 Flds_add(MockStream.id_idk, "stream_id").Flds_add(MockStream.name_idk, "stream_name")
+			.			 ConstantFlds_add("stream_type", 0)
+			,			DbMaprItm.proto_(MockStream.Instance, "subtitles", "mock_streams")
+			.			 Flds_add(MockStream.id_idk, "stream_id").Flds_add(MockStream.name_idk, "stream_name")
+			.			 ConstantFlds_add("stream_type", 1)
+			)));				
+		wtr = DbMaprWtr.new_by_url_(Db_conn_info_.Test);
+		wtr.EnvVars().Add(DbMaprWtr.Key_Mgr, mgr);
+		conn = Db_conn_pool.Instance.Get_or_new(Db_conn_info_.Test);
+		Db_qry_fxt.DeleteAll(conn, "mock_discs", "mock_titles", "mock_chapters", "mock_streams");
+	}	DbMaprMgr mgr; DbMaprWtr wtr; Db_conn conn; MockDisc disc; MockTitle title; MockChapter chapter; MockStream audio, subtitle; SrlMgr rdr;
+	@Test  public void PurgeObjTree() {
+		disc = MockDisc.new_().Id_(1);
+		Db_qry_fxt.Insert_kvo(conn, "mock_discs", Keyval_list.New_with_one("disc_id", 1));
+		DbMaprWtrUtl.PurgeObjTree(disc, mgr, conn);
+		Tfds.Eq(0, Db_qry_fxt.SelectAll_count(conn, "mock_discs"));
+	}
+	@Test  public void PurgeObjTree_deep() {
+		disc = MockDisc.new_().Id_(1);
+		Db_qry_fxt.Insert_kvo(conn, "mock_discs", Keyval_list.New_with_one("disc_id", 1));
+		Db_qry_fxt.Insert_kvo(conn, "mock_titles", Keyval_list.New_with_one("disc_id", 1).Add("title_id", 1));
+		Db_qry_fxt.Insert_kvo(conn, "mock_chapters", Keyval_list.New_with_one("disc_id", 1).Add("title_id", 2).Add("chapter_id", 3));
+		Db_qry_fxt.Insert_kvo(conn, "mock_chapters", Keyval_list.New_with_one("disc_id", 2).Add("title_id", 2).Add("chapter_id", 3));
+		DbMaprWtrUtl.PurgeObjTree(disc, mgr, conn);
+
+		Tfds.Eq(0, Db_qry_fxt.SelectAll_count(conn, "mock_discs"));
+		Tfds.Eq(0, Db_qry_fxt.SelectAll_count(conn, "mock_titles"));
+		Tfds.Eq(1, Db_qry_fxt.SelectAll_count(conn, "mock_chapters"));	// ignore chapter with disc_id=2
+	}
+	@Test  public void Save_root() {
+		disc = MockDisc.new_().Id_(1).Name_("disc");
+
+		wtr.StoreRoot(disc, "mock_discs");
+		Db_qry_fxt.tst_Select(conn, "mock_discs", Db_mock_row.vals_only_(1, "disc"));
+	}
+	@Test  public void Save_subs() {
+		disc = MockDisc.new_().Id_(1).Name_("disc");
+		title = MockTitle.new_().Id_(2).Name_("title").Disc_(disc);
+
+		wtr.StoreRoot(disc, "mock_discs");
+		Db_qry_fxt.tst_Select(conn, "mock_discs", Db_mock_row.vals_only_(1, "disc"));
+		Db_qry_fxt.tst_Select(conn, "mock_titles", Db_mock_row.vals_only_(1, 2, "title"));
+	}
+	@Test  public void Save_deep() {
+		disc = MockDisc.new_().Id_(1).Name_("disc");
+		title = MockTitle.new_().Id_(2).Name_("title").Disc_(disc);
+		chapter = MockChapter.new_().Id_(3).Name_("chap").Title_(title);
+		audio = MockStream.new_().Id_(4).Name_("audio").Title_(title.Audios());
+		subtitle = MockStream.new_().Id_(5).Name_("subtitle").Title_(title.Subtitles());
+
+		wtr.StoreRoot(disc, "mock_discs");
+		Db_qry_fxt.tst_Select(conn, "mock_discs", Db_mock_row.vals_only_(1, "disc"));
+		Db_qry_fxt.tst_Select(conn, "mock_titles", Db_mock_row.vals_only_(1, 2, "title"));
+		Db_qry_fxt.tst_Select(conn, "mock_chapters", Db_mock_row.vals_only_(1, 2, 3, "chap"));
+		Db_qry_fxt.tst_Select(conn, "mock_streams"
+			, Db_mock_row.vals_only_(1, 2, null, 4, "audio")
+			, Db_mock_row.vals_only_(1, 2, null, 5, "subtitle")
+			);
+	}
+	@Test  public void Load_root() {
+		rdr = rdr_();
+		Db_qry_fxt.Insert_kvo(conn, "mock_discs", Keyval_list.New_with_one("disc_id", 1).Add("disc_name", "name"));
+		disc = (MockDisc)rdr.StoreRoot(MockDisc.Instance, null);
+
+		Tfds.Eq(1, disc.Id());
+		Tfds.Eq("name", disc.Name());
+		Tfds.Eq(0, disc.Titles().Count());
+	}
+	@Test  public void Load_subs() {
+		rdr = rdr_();
+		Db_qry_fxt.Insert_kvo(conn, "mock_discs", Keyval_list.New_with_one("disc_id", 1).Add("disc_name", "name"));
+		Db_qry_fxt.Insert_kvo(conn, "mock_titles", Keyval_list.New_with_one("disc_id", 1).Add("title_id", 1).Add("title_name", "title1"));
+		Db_qry_fxt.Insert_kvo(conn, "mock_titles", Keyval_list.New_with_one("disc_id", 1).Add("title_id", 2).Add("title_name", "title2"));
+		disc = (MockDisc)rdr.StoreRoot(MockDisc.Instance, null);
+
+		Tfds.Eq(1, disc.Id());
+		Tfds.Eq("name", disc.Name());
+		Tfds.Eq(2, disc.Titles().Count());
+		Tfds.Eq("title1", ((MockTitle)disc.Titles().Get_at(0)).Name());
+		Tfds.Eq("title2", ((MockTitle)disc.Titles().Get_at(1)).Name());
+	}
+	@Test  public void Load_deep() {
+		rdr = rdr_();
+		Db_qry_fxt.Insert_kvo(conn, "mock_discs", Keyval_list.New_with_one("disc_id", 1).Add("disc_name", "name"));
+		Db_qry_fxt.Insert_kvo(conn, "mock_titles", Keyval_list.New_with_one("disc_id", 1).Add("title_id", 1).Add("title_name", "title1"));
+		Db_qry_fxt.Insert_kvo(conn, "mock_chapters", Keyval_list.New_with_one("disc_id", 1).Add("title_id", 1).Add("chapter_id", 3).Add("chapter_name", "chapter1"));
+		Db_qry_fxt.Insert_kvo(conn, "mock_streams", Keyval_list.New_with_one("disc_id", 1).Add("title_id", 1).Add("stream_id", 4).Add("stream_type", 0).Add("stream_name", "audio1"));
+		Db_qry_fxt.Insert_kvo(conn, "mock_streams", Keyval_list.New_with_one("disc_id", 1).Add("title_id", 1).Add("stream_id", 5).Add("stream_type", 1).Add("stream_name", "subtitle1"));
+		disc = (MockDisc)rdr.StoreRoot(MockDisc.Instance, null);
+
+		Tfds.Eq(1, disc.Id());
+		Tfds.Eq("name", disc.Name());
+		Tfds.Eq(1, disc.Titles().Count());
+		MockTitle t = ((MockTitle)disc.Titles().Get_at(0));
+		Tfds.Eq("title1", t.Name());
+		Tfds.Eq("chapter1", ((MockChapter)t.Chapters().Get_at(0)).Name());
+		Tfds.Eq(1, t.Audios().Count());
+		Tfds.Eq(1, t.Subtitles().Count());
+		Tfds.Eq("audio1", ((MockStream)t.Audios().Get_at(0)).Name());
+		Tfds.Eq("subtitle1", ((MockStream)t.Subtitles().Get_at(0)).Name());
+	}
+	DbMaprRdr rdr_() {
+		DbMaprRdr rv = DbMaprRdr.new_(Db_conn_info_.Test, Db_crt_.New_eq("disc_id", 1));
+		rv.EnvVars().Add(DbMaprWtr.Key_Mgr, mgr);
+		return rv;
+	}
+}

140_dbs/src/gplx/core/stores/DbMaprRdr.java

@@ -13,3 +13,108 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.core.stores; import gplx.*; import gplx.core.*;
+import gplx.core.criterias.*; import gplx.dbs.*; import gplx.core.gfo_ndes.*;
+public class DbMaprRdr extends DataRdr_base implements SrlMgr {
+	@Override public String NameOfNode() {return "DbMaprRdr";}
+	@Override public Object StoreRoot(SrlObj subProto, String key) {
+		mgr = (DbMaprMgr)this.EnvVars().Get_by_or_fail(DbMaprWtr.Key_Mgr);
+		DbMaprItm rootMapr = mgr.Root();
+
+		GfoNde tbl = GetTbl(rootMapr, rootCrt); int subsCount = tbl.Subs().Count(); if (subsCount == 0) return null; if (subsCount > 1) throw Err_.new_wo_type("criteria returned > 1 row", "criteria", rootCrt.To_str(), "subsCount", subsCount);
+		SrlObj root = subProto.SrlObj_New(null);
+		mgr.EnvStack_add(rootMapr, root); RowStack_add(tbl, 0);
+		root.SrlObj_Srl(this);
+		mgr.Clear(); rowStack.Clear();
+		return root;
+	}
+	@Override public void SrlList(String subPropKey, List_adp list, SrlObj subProto, String itmKey) {
+		DbMaprItm curMapr = (DbMaprItm)mgr.MaprStack().Get_at_last();
+		DbMaprItm subMapr = curMapr.Subs_get(subPropKey);
+		list.Clear();
+
+		Criteria crit = MakeCrt(mgr, subMapr);
+		GfoNde tbl = GetTbl(subMapr, crit);
+		int tblLen = tbl.Subs().Count();
+		for (int i = 0; i < tblLen; i++) {
+			SrlObj sub = (SrlObj)subProto.SrlObj_New(null);
+			GfoNde subRow = tbl.Subs().FetchAt_asGfoNde(i);
+			mgr.EnvStack_add(subMapr, sub); rowStack.Add(subRow);
+			sub.SrlObj_Srl(this); list.Add(sub);
+			mgr.EnvStack_del(subMapr, sub); List_adp_.Del_at_last(rowStack);
+		}
+	}
+	Criteria MakeCrt(DbMaprMgr mgr, DbMaprItm mapr) {
+		Criteria rv = null, cur = null;
+		List_adp list = GetIdxFlds(mgr, mapr);
+		for (Object kvObj : list) {
+			Keyval kv = (Keyval)kvObj;
+			cur = Db_crt_.New_eq(kv.Key(), kv.Val());
+			rv = (rv == null) ? cur : Criteria_.And(rv, cur);
+		}
+		return rv;
+	}
+	List_adp GetIdxFlds(DbMaprMgr mgr, DbMaprItm curMapr) {
+		List_adp rv = List_adp_.New();
+		int maprStackCount = mgr.MaprStack().Count() - 0; // -1 b/c current is added to stack
+		for (int i = 0; i < maprStackCount; i ++) {
+			DbMaprItm mapr = (DbMaprItm)mgr.MaprStack().Get_at(i);
+			SrlObj gobj = (SrlObj)mgr.OwnerStack().Get_at(i);
+			for (Object argObj : mapr.ContextFlds()) {
+				DbMaprArg arg = (DbMaprArg)argObj;
+				Object propVal = Gfo_invk_.Invk_by_key((Gfo_invk)gobj, arg.ObjProp());
+				rv.Add(Keyval_.new_(arg.DbFld(), propVal));
+			}					
+		}
+		for (Object argObj : curMapr.ConstantFlds()) {
+			Keyval arg = (Keyval)argObj;
+			rv.Add(arg);
+		}
+		return rv;
+	}
+	GfoNde GetTbl(DbMaprItm mapr, Criteria crit) {
+		String key = mapr.TableName();			
+		GfoNde tblByRootCrt = GfoNde_.as_(tables.Get_by(key));
+		if (tblByRootCrt == null) {
+			DataRdr dbRdr = null;
+			try {
+				dbRdr = conn.Exec_qry_as_old_rdr(Db_qry_.select_().From_(mapr.TableName()).Where_(rootCrt));
+				tblByRootCrt = GfoNde_.rdr_(dbRdr);
+			}
+			finally {dbRdr.Rls();}
+			tables.Add(key, tblByRootCrt);
+		}
+		GfoNde rv = GfoNde_.tbl_(mapr.TableName(), tblByRootCrt.Flds());
+		for (int i = 0; i < tblByRootCrt.Subs().Count(); i++) {
+			GfoNde row = tblByRootCrt.Subs().FetchAt_asGfoNde(i);
+			if (crit.Matches(row)) rv.Subs().Add(row);
+		}
+		return rv;
+	}
+	void RowStack_add(GfoNde tbl, int i) {
+		GfoNdeList ndeList = tbl.Subs(); if (i >= ndeList.Count()) throw Err_.new_missing_idx(i, ndeList.Count());
+		rowStack.Add(tbl.Subs().FetchAt_asGfoNde(i));
+	}
+	@Override public Object Read(String key) {
+		DbMaprItm mapr = (DbMaprItm)mgr.MaprStack().Get_at_last();
+		GfoNde row = (GfoNde)rowStack.Get_at_last();
+		DbMaprArg arg = mapr.Flds_get(key);
+		Object dbVal = null; try {dbVal = row.Read(arg.DbFld());} catch (Exception e) {throw Err_.new_exc(e, "db", "failed to read dbVal from row", "key", key, "fld", arg.DbFld());}
+		return dbVal;
+	}
+	@Override public DataRdr Subs_byName_moveFirst(String name) {throw Err_.new_unimplemented();}
+	@Override public DataRdr Subs() {throw Err_.new_unimplemented();}
+	@Override public int FieldCount() {throw Err_.new_unimplemented();}
+	@Override public String KeyAt(int i) {throw Err_.new_unimplemented();}
+	@Override public Object ReadAt(int i) {throw Err_.new_unimplemented();}
+	@Override public Keyval KeyValAt(int i) {throw Err_.new_unimplemented();}
+	@Override public SrlMgr SrlMgr_new(Object o) {return new DbMaprRdr();}
+	Hash_adp tables = Hash_adp_.New();
+	Db_conn conn; Criteria rootCrt;
+	DbMaprMgr mgr; List_adp rowStack = List_adp_.New();
+	public static DbMaprRdr new_(Db_conn_info dbInfo, Criteria rootCrt) {
+		DbMaprRdr rv = new DbMaprRdr();
+		rv.conn = Db_conn_pool.Instance.Get_or_new(dbInfo); rv.rootCrt = rootCrt;
+		return rv;
+	}	DbMaprRdr() {}
+}

140_dbs/src/gplx/core/stores/DbMaprWtr.java

@@ -13,3 +13,101 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.core.stores; import gplx.*; import gplx.core.*;
+import gplx.core.criterias.*; import gplx.core.gfo_ndes.*;
+import gplx.dbs.*; import gplx.dbs.qrys.*;
+public class DbMaprWtr extends DataWtr_base implements DataWtr {
+	public void InitWtr(String key, Object val) {}
+	@Override public Object StoreRoot(SrlObj root, String key) {
+		mgr = (DbMaprMgr)this.EnvVars().Get_by_or_fail(DbMaprWtr.Key_Mgr);
+		DbMaprWtrUtl.PurgeObjTree(root, mgr, conn);
+		WriteGfoObj(root, mgr.Root());
+		mgr.Clear();
+		return null;
+	}
+	@Override public void SrlList(String subPropKey, List_adp list, SrlObj subProto, String itmKey) {
+		DbMaprItm ownerMapr = (DbMaprItm)mgr.MaprStack().Get_at_last();
+		DbMaprItm subMapr = ownerMapr.Subs_get(subPropKey);
+
+		for (Object subObj : list) {
+			SrlObj sub = (SrlObj)subObj;
+			WriteGfoObj(sub, subMapr);
+		}
+	}
+	void WriteGfoObj(SrlObj gobj, DbMaprItm mapr) {
+		mgr.EnvStack_add(mapr, gobj);
+		this.WriteNodeBgn(mapr.TableName());
+		this.WriteContextFlds();
+		gobj.SrlObj_Srl(this);
+		this.WriteNodeEnd();
+		mgr.EnvStack_del(mapr, gobj);
+	}
+	void WriteContextFlds() {
+		int maprStackCount = mgr.MaprStack().Count() - 1; // -1 b/c current is added to stack
+		for (int i = 0; i < maprStackCount; i ++) {
+			DbMaprItm mapr = (DbMaprItm)mgr.MaprStack().Get_at(i);
+			SrlObj gobj = (SrlObj)mgr.OwnerStack().Get_at(i);
+			for (Object argObj : mapr.ContextFlds()) {
+				DbMaprArg arg = (DbMaprArg)argObj;
+				Object argVal = Gfo_invk_.Invk_by_key((Gfo_invk)gobj, arg.ObjProp());
+				this.WriteDataVal(arg.DbFld(), argVal);
+			}					
+		}
+	}
+	@Override public void WriteNodeBgn(String v) {
+		if (insertCmd != null) insertCmd.Exec_qry(conn);		// occurs for nodes; ex: new title starts; commit changes for own disc
+		curTableName = v;
+		insertCmd = null;
+	}
+	@Override public void WriteData(String name, Object val) {
+		DbMaprItm ownerMapr = (DbMaprItm)mgr.MaprStack().Get_at_last();
+		String fld = ""; try {fld = ownerMapr.Flds_get(name).DbFld();} catch (Exception e) {throw Err_.new_exc(e, "db", "failed to fetch fld from mapr", "key", name);}
+		WriteDataVal(fld, val);
+	}
+	void WriteDataVal(String fld, Object val) {
+		if (insertCmd == null) insertCmd = Db_qry_.insert_(curTableName);
+		if (Type_.Eq_by_obj(val, String.class))
+			insertCmd.Val_obj_type(fld, val, Db_val_type.Tid_varchar);
+		else
+			insertCmd.Val_obj(fld, val);
+	}
+	@Override public void WriteNodeEnd() {
+		if (insertCmd != null) insertCmd.Exec_qry(conn);		// occurs for nodes and leaves; for nodes, insertCmd will be null (committed by last leaf)
+		insertCmd = null;
+	}
+	public void WriteTableBgn(String name, GfoFldList fields) {}
+	public void WriteLeafBgn(String leafName) {}
+	public void WriteLeafEnd() {}
+	public void Clear() {}
+	public String To_str() {return "";}
+	@Override public SrlMgr SrlMgr_new(Object o) {return new DbMaprWtr();}
+	DbMaprMgr mgr; Db_conn conn; String curTableName; Db_qry_insert insertCmd;		
+	public static DbMaprWtr new_by_url_(Db_conn_info url) {
+		DbMaprWtr rv = new DbMaprWtr();
+		rv.conn = Db_conn_pool.Instance.Get_or_new(url);
+		return rv;
+	}	DbMaprWtr() {}
+	public static final    String Key_Mgr = "DbMapr.mgr";
+}
+class DbMaprWtrUtl {
+	public static void PurgeObjTree(SrlObj root, DbMaprMgr mgr, Db_conn conn) {
+		Criteria crt = MakeCriteria(root, mgr.RootIndexFlds());
+		PurgeObj(mgr.Root(), crt, conn);
+	}
+	static Criteria MakeCriteria(SrlObj root, DbMaprArg[] objRootIdxFlds) {
+		Criteria rv = null;
+		for (DbMaprArg arg : objRootIdxFlds) {
+			Object argVal = Gfo_invk_.Invk_by_key((Gfo_invk)root, arg.ObjProp());
+			Criteria cur = Db_crt_.New_eq(arg.DbFld(), argVal);
+			rv = (rv == null) ? cur : Criteria_.And(rv, cur);
+		}
+		return rv;
+	}
+	static void PurgeObj(DbMaprItm mapr, Criteria crt, Db_conn conn) {
+		Db_qry_.delete_(mapr.TableName(), crt).Exec_qry(conn);
+		for (Object subObj : mapr.Subs()) {
+			DbMaprItm sub = (DbMaprItm)subObj;
+			PurgeObj(sub, crt, conn);
+		}
+	}
+}

140_dbs/src/gplx/core/stores/Db_data_rdr.java

@@ -13,3 +13,67 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.core.stores; import gplx.*; import gplx.core.*;
+import java.sql.Date;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Timestamp;
+import java.util.GregorianCalendar;
+import gplx.dbs.*;
+public class Db_data_rdr extends DataRdr_base implements DataRdr {
+	@Override public String NameOfNode() {return commandText;} public String To_str() {return commandText;} private String commandText;
+		private ResultSet rdr;
+	private int fieldCount;
+	@Override public int FieldCount() {return fieldCount;}
+	@Override public String KeyAt(int i) {
+		String rv = null; 
+		try {rv = rdr.getMetaData().getColumnLabel(i + List_adp_.Base1);}
+		catch (SQLException e) {throw Err_.new_exc(e, "db", "get columnName failed", "i", i, "commandText", commandText);}
+		return rv;
+	}
+	@Override public Object ReadAt(int i) {
+		Object rv;
+		try {rv = rdr.getObject(i + List_adp_.Base1);} catch(Exception exc) {throw Err_.new_wo_type("could not read val from dataReader; idx not found or rdr not open", "idx", i, "sql", commandText);}
+		return rv;
+	}
+	@Override public Object Read(String key) {
+		Object rv;
+		try {rv = rdr.getObject(key);} catch(Exception exc) {throw Err_.new_wo_type("could not read val from dataReader; key not found or rdr may not be open", "key", key, "sql", commandText);}
+		return rv;
+	}
+	@Override public DateAdp ReadDate(String key) {
+		Object o = this.Read(key);
+		Timestamp ts = (Timestamp)o;
+		GregorianCalendar g = new GregorianCalendar();		
+		g.setTime(ts);
+		return DateAdp_.dateTime_(g);
+	}
+	@Override public Decimal_adp ReadDecimal(String key) {return Decimal_adp_.db_(this.Read(key));}
+	@Override public gplx.core.ios.streams.Io_stream_rdr ReadRdr(String key) {
+		try {
+			java.io.InputStream input_stream = rdr.getBinaryStream(key);			
+			return gplx.core.ios.streams.Io_stream_rdr_.New__raw(input_stream);
+		}
+		catch (SQLException e) {return gplx.core.ios.streams.Io_stream_rdr_.Noop;}
+	}
+	
+	public boolean MoveNextPeer() {
+		try {return rdr.next();}
+		catch (Exception e) {throw Err_.new_exc(e, "db", "could not move next; check column casting error in SQL", "sql", commandText);}
+	}
+	@Override public DataRdr Subs()							{throw Err_.new_unimplemented();}
+	public DataRdr Subs_byName(String fld)					{throw Err_.new_unimplemented();}
+	@Override public DataRdr Subs_byName_moveFirst(String fld)		{throw Err_.new_unimplemented();}		
+	public void Rls() {
+		try {rdr.close();}
+		catch (SQLException e) {throw Err_.new_exc(e, "db", "reader dispose failed", "commandText", commandText);}
+		this.EnvVars().Clear();
+	}
+	@gplx.Internal protected Db_data_rdr ctor_db_data_rdr(ResultSet rdr, String commandText) {
+		this.rdr = rdr; this.commandText = commandText; this.Parse_set(false);
+		try {fieldCount = this.rdr.getMetaData().getColumnCount();}
+		catch (SQLException e) {Err_.new_exc(e, "xo", "get columnCount failed", "commandText", commandText);}
+		return this;
+	}
+	@Override public SrlMgr SrlMgr_new(Object o) {return new Db_data_rdr();}
+}

140_dbs/src/gplx/core/stores/Db_data_rdr_.java

@@ -13,3 +13,8 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.core.stores; import gplx.*; import gplx.core.*;
+import java.sql.ResultSet;
+public class Db_data_rdr_ {
+		public static Db_data_rdr new_(ResultSet rdr, String commandText) {return new Db_data_rdr().ctor_db_data_rdr(rdr, commandText);}
+	}

140_dbs/src/gplx/core/stores/MockDiscObj.java

@@ -13,3 +13,116 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.core.stores; import gplx.*; import gplx.core.*;
+class MockDisc implements SrlObj, Gfo_invk {
+	public int Id() {return id;} public MockDisc Id_(int val) {id = val; return this;} int id; public static final    String id_idk = "id";
+	public String Name() {return name;} public MockDisc Name_(String val) {name = val; return this;} private String name; public static final    String name_idk = "name";
+	public List_adp Titles() {return titles;} List_adp titles = List_adp_.New(); public static final    String titles_idk = "titles";
+	public static final    MockDisc Instance = new MockDisc(); MockDisc() {}
+	public SrlObj SrlObj_New(Object o)	{return new MockDisc();}
+	public Object Invk(GfsCtx ctx, int ikey, String k, GfoMsg m) {
+		if		(ctx.Match(k, id_idk))				return Id();
+		else if	(ctx.Match(k, name_idk))			return Name();
+		else if	(ctx.Match(k, titles_idk))			return Titles();
+		else return Gfo_invk_.Rv_unhandled;
+	}
+//		public Object Srl_new(GfsCtx ctx) {return new MockDisc();}
+//		public void Srl(GfsCtx ctx, int ikey, String k, GfoMsg m) {
+//			id = m.ReadIntOr(id_idk, id);
+//			name = m.ReadStrOr(name_idk, name);
+//			for (int i = 0; i < m.Subs_count(); i++) {
+//				GfoMsg subMsg = m.Subs_getAt(i);
+//				if		(String_.Eq(subMsg.Key(), titles_idk)) DoIt(ctx, ikey, k, subMsg, titles, MockTitle.Instance, "title");
+//			}			
+//		}
+//		public static void DoIt(GfsCtx ctx, int ikey, String k, GfoMsg m, List_adp list, Object o, String subKey) {
+//		}
+	public void SrlObj_Srl(SrlMgr mgr) {
+		id = mgr.SrlIntOr(id_idk, id);
+		name = mgr.SrlStrOr(name_idk, name);
+		mgr.SrlList(titles_idk, titles, MockTitle.Instance, "title");
+	}
+	public static MockDisc new_() {
+		MockDisc rv = new MockDisc();
+		return rv;
+	}
+}
+class MockTitle implements SrlObj, Gfo_invk {
+	public int Id() {return id;} public MockTitle Id_(int val) {id = val; return this;} int id; public static final    String id_idk = "id";
+	public String Name() {return name;} public MockTitle Name_(String val) {name = val; return this;} private String name; public static final    String name_idk = "name";
+	public List_adp Chapters() {return chapters;} List_adp chapters = List_adp_.New(); public static final    String chapters_idk = "chapters";
+	public List_adp Audios() {return audios;} List_adp audios = List_adp_.New(); public static final    String audios_idk = "audios";
+	public List_adp Subtitles() {return subtitles;} List_adp subtitles = List_adp_.New(); public static final    String subtitles_idk = "subtitles";
+	public MockTitle Disc_(MockDisc disc) {disc.Titles().Add(this); return this;}
+	public static MockTitle new_() {
+		MockTitle rv = new MockTitle();
+		return rv;
+	}
+	public static final    MockTitle Instance = new MockTitle(); MockTitle() {}
+	public SrlObj SrlObj_New(Object o)	{return new MockTitle();}
+	public Object Invk(GfsCtx ctx, int ikey, String k, GfoMsg m) {
+		if		(ctx.Match(k, id_idk))				return Id();
+		else if	(ctx.Match(k, name_idk))			return Name();
+		else if	(ctx.Match(k, chapters_idk))		return Chapters();
+		else if	(ctx.Match(k, audios_idk))			return Audios();
+		else if	(ctx.Match(k, subtitles_idk))		return Subtitles();
+		else return Gfo_invk_.Rv_unhandled;
+	}
+//		public void Srl(GfsCtx ctx, int ikey, String k, GfoMsg m) {
+//			id = m.ReadIntOr(id_idk, id);
+//			name = m.ReadStrOr(name_idk, name);
+//			for (int i = 0; i < m.Subs_count(); i++) {
+//				GfoMsg subMsg = m.Subs_getAt(i);
+//				if		(String_.Eq(subMsg.Key(), chapters_idk))	MockDisc.DoIt(ctx, ikey, k, subMsg, chapters, MockChapter.Instance, "chapter");
+//				else if	(String_.Eq(subMsg.Key(), audios_idk))		MockDisc.DoIt(ctx, ikey, k, subMsg, audios, MockStream.Instance, "audio");
+//				else if	(String_.Eq(subMsg.Key(), subtitles_idk))	MockDisc.DoIt(ctx, ikey, k, subMsg, subtitles, MockStream.Instance, "subtitle");
+//			}			
+//		}
+	public void SrlObj_Srl(SrlMgr mgr) {
+		id = mgr.SrlIntOr(id_idk, id);
+		name = mgr.SrlStrOr(name_idk, name);
+		mgr.SrlList(chapters_idk, chapters, MockChapter.Instance, "chapter");
+		mgr.SrlList(audios_idk, audios, MockStream.Instance, "audio");
+		mgr.SrlList(subtitles_idk, subtitles, MockStream.Instance, "subtitle");
+	}
+}
+class MockChapter implements SrlObj, Gfo_invk {
+	public int Id() {return id;} public MockChapter Id_(int val) {id = val; return this;} int id; public static final    String id_idk = "id";
+	public String Name() {return name;} public MockChapter Name_(String val) {name = val; return this;} private String name; public static final    String name_idk = "name";
+	public MockChapter Title_(MockTitle title) {title.Chapters().Add(this); return this;}
+	public static final    MockChapter Instance = new MockChapter(); MockChapter() {}
+	public static MockChapter new_() {
+		MockChapter rv = new MockChapter();
+		return rv;
+	}
+	public SrlObj SrlObj_New(Object o) {return new MockChapter();}
+	public Object Invk(GfsCtx ctx, int ikey, String k, GfoMsg m) {
+		if		(ctx.Match(k, id_idk))				return Id();
+		else if	(ctx.Match(k, name_idk))			return Name();
+		else return Gfo_invk_.Rv_unhandled;
+	}
+	public void SrlObj_Srl(SrlMgr mgr) {
+		id = mgr.SrlIntOr(id_idk, id);
+		name = mgr.SrlStrOr(name_idk, name);
+	}
+}
+class MockStream implements SrlObj, Gfo_invk {
+	public int Id() {return id;} public MockStream Id_(int val) {id = val; return this;} int id; public static final    String id_idk = "id";
+	public String Name() {return name;} public MockStream Name_(String val) {name = val; return this;} private String name; public static final    String name_idk = "name";
+	public MockStream Title_(List_adp list) {list.Add(this); return this;}
+	public static final    MockStream Instance = new MockStream(); MockStream() {}
+	public static MockStream new_() {
+		MockStream rv = new MockStream();
+		return rv;
+	}
+	public SrlObj SrlObj_New(Object o)	{return new MockStream();}
+	public Object Invk(GfsCtx ctx, int ikey, String k, GfoMsg m) {
+		if		(ctx.Match(k, id_idk))				return Id();
+		else if	(ctx.Match(k, name_idk))			return Name();
+		else return Gfo_invk_.Rv_unhandled;
+	}
+	public void SrlObj_Srl(SrlMgr mgr) {
+		id = mgr.SrlIntOr(id_idk, id);
+		name = mgr.SrlStrOr(name_idk, name);
+	}
+}

140_dbs/src/gplx/dbs/Db_attach_itm.java

@@ -0,0 +1,26 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+public class Db_attach_itm {
+	public Db_attach_itm(String key, Io_url url) {
+		this.Key = key; this.Url = url;
+	}
+	public Db_attach_itm(String key, Db_conn conn) {
+		this.Key = key; this.Url = gplx.dbs.engines.sqlite.Sqlite_conn_info.To_url(conn);
+	}
+	public final String Key;
+	public final Io_url Url;
+}

140_dbs/src/gplx/dbs/Db_attach_mgr.java

@@ -0,0 +1,120 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+import gplx.dbs.sqls.*; import gplx.dbs.sqls.itms.*;
+public class Db_attach_mgr {
+	private Db_conn main_conn; private Io_url main_conn_url;
+	private final    Ordered_hash links_hash = Ordered_hash_.New();
+	private final    List_adp attach_list = List_adp_.New();
+	public Db_attach_mgr() {}
+	public Db_attach_mgr(Db_conn main_conn, Db_attach_itm... links_ary) {
+		this.Conn_main_(main_conn);
+		this.Conn_links_(links_ary);
+	}
+	public Db_conn Conn_main() {return main_conn;}
+	public Db_attach_mgr Conn_main_(Db_conn conn) {
+		this.main_conn = conn; this.main_conn_url = Db_conn_info_.To_url(conn.Conn_info());
+		return this;
+	}
+	public Db_attach_mgr Conn_links_(Db_attach_itm... itms_ary) {
+		links_hash.Clear();
+		int len = itms_ary.length;
+		for (int i = 0; i < len; ++i) {
+			Db_attach_itm itm = itms_ary[i];
+			links_hash.Add(itm.Key, itm);
+		}
+		return this;
+	}
+	public void Attach() {
+		int len = attach_list.Len();
+		for (int i = 0; i < len; ++i) {
+			Db_attach_itm itm = (Db_attach_itm)attach_list.Get_at(i);
+			main_conn.Env_db_attach(itm.Key, itm.Url);
+		}
+	}
+	public void Detach() {
+		int len = attach_list.Len();
+		for (int i = 0; i < len; ++i) {
+			Db_attach_itm itm = (Db_attach_itm)attach_list.Get_at(i);
+			main_conn.Env_db_detach(itm.Key);
+		}
+		attach_list.Clear();	// clear list so multiple detachs don't fail
+	}
+	public String Resolve_sql(String sql) {
+		attach_list.Clear();
+		int hash_len = links_hash.Count();
+		for (int i = 0; i < hash_len; ++i) {
+			Db_attach_itm attach_itm = (Db_attach_itm)links_hash.Get_at(i);
+			String tkn = "<" + attach_itm.Key + ">";
+			if (String_.Has(sql, tkn)) {
+				Io_url attach_url = attach_itm.Url;
+				String repl = "";
+				if (!attach_url.Eq(main_conn_url)) {
+					repl = attach_itm.Key + ".";
+					attach_list.Add(attach_itm);
+				}
+				sql = String_.Replace(sql, tkn, repl);
+			}
+		}
+		attached_sql = sql;
+		return sql;
+	}
+	public Db_attach_mgr Exec_sql_w_msg(String msg, String sql, Object... args) {
+		Gfo_usr_dlg_.Instance.Plog_many("", "", msg);
+		Exec_sql(sql, args);
+		return this;
+	}
+	public Db_attach_mgr Exec_sql(String sql, Object... args) {
+		String attach_sql = String_.Format(Resolve_sql(sql), args);
+		this.Attach();
+		try {main_conn.Exec_sql(attach_sql);}
+		finally {this.Detach();}
+		return this;
+	}
+	public String Test__attach_sql() {return attached_sql;} private String attached_sql;
+	public String[] Test__attach_list_keys() {
+		int rv_len = attach_list.Count();
+		String[] rv = new String[rv_len];
+		for (int i = 0; i < rv_len; ++i) {
+			Db_attach_itm itm = (Db_attach_itm)attach_list.Get_at(i);
+			rv[i] = itm.Key;
+		}
+		return rv;
+	}
+	public Db_stmt Test__make_stmt_and_attach(Db_qry qry, gplx.dbs.sqls.itms.Sql_from_clause from_itm) {	// NOTE: tries to do attach via DOM not SQL 
+		attach_list.Clear();
+		Sql_qry_wtr sql_wtr = main_conn.Engine().Sql_wtr();
+		List_adp from_tbls = from_itm.Tbls;
+		int from_tbls_len = from_tbls.Count();
+		for (int i = 0; i < from_tbls_len; ++i) {
+			Sql_tbl_itm from_tbl = (Sql_tbl_itm)from_tbls.Get_at(i);
+			String from_tbl_db = from_tbl.Db;
+			if (String_.Eq(Sql_tbl_itm.Db__null, from_tbl_db)) continue;	// tbl does not have db defined; only "tbl" not "db.tbl"; skip
+			Db_attach_itm attach_itm = (Db_attach_itm)links_hash.Get_by(from_tbl_db); if (attach_itm == null) throw Err_.new_("dbs", "qry defines an unknown database for attach_wkr", "from_tbl_db", from_tbl_db, "sql", qry.To_sql__exec(sql_wtr)); 
+			if (attach_itm.Url.Eq(main_conn_url)) // attach_db same as conn; blank db, so "tbl", not "db.tbl"
+				from_tbl.Db_enabled = false;
+			else
+				attach_list.Add(attach_itm);
+		}
+		attached_sql = sql_wtr.To_sql_str(qry, true);
+		this.Attach();
+		for (int i = 0; i < from_tbls_len; ++i) {	// reverse blanking from above
+			Sql_tbl_itm from_tbl = (Sql_tbl_itm)from_tbls.Get_at(i);
+			from_tbl.Db_enabled = true;
+		}
+		return main_conn.Stmt_sql(attached_sql);
+	}
+}

140_dbs/src/gplx/dbs/Db_attach_mgr__tst.java

@@ -0,0 +1,57 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+import org.junit.*; import gplx.core.tests.*; import gplx.dbs.qrys.*;
+public class Db_attach_mgr__tst {
+	private final    Db_attach_mgr__fxt fxt = new Db_attach_mgr__fxt();
+	@Test  public void Basic() {
+		Db_qry__select_cmd qry = Db_qry_.select_()
+			.Cols_w_tbl_("t1", "fld_1")
+			.Cols_w_tbl_("t2", "fld_2")
+			.Cols_w_tbl_("t3", "fld_3")
+			.From_("db_1", "tbl_1", "t1")
+			.Join_("db_2", "tbl_2", "t2", Db_qry_.New_join__same("t1", "fld_2"))
+			.Join_("db_3", "tbl_3", "t3", Db_qry_.New_join__same("t1", "fld_3"))
+			.Join_(		   "tbl_4", "t4", Db_qry_.New_join__same("t1", "fld_4"))
+			;
+		fxt.Init("db_2", fxt.Make__other("db_1"), fxt.Make__other("db_2"), fxt.Make__other("db_3"));
+		fxt.Test__make_stmt_and_attach(qry
+		, "SELECT t1.fld_1, t2.fld_2, t3.fld_3 "
+		+ "FROM db_1.tbl_1 t1 "
+		+     "INNER JOIN tbl_2 t2 ON t1.fld_2 = t2.fld_2 "		// NOTE: curr is db_2 so do not prefix tbl_2 with db_2; fails if "db_2.tbl_2"
+		+     "INNER JOIN db_3.tbl_3 t3 ON t1.fld_3 = t3.fld_3 "
+		+     "INNER JOIN tbl_4 t4 ON t1.fld_4 = t4.fld_4"
+		, String_.Ary("db_1", "db_3")							// NOTE: no "db_2"
+		);
+	}
+}
+class Db_attach_mgr__fxt {
+	private Db_attach_mgr mgr;
+	public Db_attach_mgr__fxt() {
+		Db_conn_bldr.Instance.Reg_default_mem();
+	}
+	public Db_conn Make__conn(String key) {return Db_conn_bldr.Instance.New(Io_url_.mem_fil_(key));}
+	public Db_attach_itm Make__other(String key) {return new Db_attach_itm(key, Io_url_.mem_fil_("mem/" + key));}
+	public void Init(String conn_key, Db_attach_itm... ary) {
+		Db_conn conn = Make__conn(conn_key);
+		mgr = new Db_attach_mgr(conn, ary);
+	}
+	public void Test__make_stmt_and_attach(Db_qry__select_cmd qry, String expd_sql, String[] expd_dbs) {
+		mgr.Test__make_stmt_and_attach(qry, qry.From());
+		Gftest.Eq__str(expd_sql, mgr.Test__attach_sql());
+		Gftest.Eq__ary(expd_dbs, mgr.Test__attach_list_keys());
+	}
+}

140_dbs/src/gplx/dbs/Db_cmd_mode.java

@@ -0,0 +1,40 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+public class Db_cmd_mode {
+	Db_cmd_mode(int val) {this.val = val;}
+	public int Val() {return val;} int val;
+	public Db_cmd_mode MarkUpdated() {return this == Retrieved ? Updated : this;} // Created/Deleted noops
+	public boolean Modified() {return this == Created || this == Updated;}
+	public static final byte Tid_create = 1, Tid_update = 2, Tid_delete = 3, Tid_ignore = 4;
+	public static final Db_cmd_mode
+	  Created		= new Db_cmd_mode(Tid_create)
+	, Updated		= new Db_cmd_mode(Tid_update)
+	, Deleted		= new Db_cmd_mode(Tid_delete)
+	, Retrieved		= new Db_cmd_mode(Tid_ignore)
+	;
+	public static byte To_update(byte cur) {
+		switch (cur) {
+			case Tid_create:					// ignore update if item is already marked for create
+			case Tid_delete:					// ignore update if item is already marked for delete (might want to throw error)
+							return cur;		
+			case Tid_ignore:					// must mark for update
+			case Tid_update:					// return self
+							return Tid_update;
+			default:		throw Err_.new_unhandled(cur);
+		}
+	}
+}

140_dbs/src/gplx/dbs/Db_conn.java

@@ -0,0 +1,157 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+import gplx.core.stores.*; import gplx.dbs.metas.*; import gplx.dbs.engines.*; import gplx.dbs.qrys.*; import gplx.dbs.sys.*; import gplx.dbs.conn_props.*; import gplx.dbs.qrys.bats.*;
+public class Db_conn {
+	private final    List_adp rls_list = List_adp_.New();
+	public Db_conn(Db_engine engine) {
+		this.engine = engine;
+		this.sys_mgr = new Db_sys_mgr(this);
+	}
+	public Db_conn_info			Conn_info()				{return engine.Conn_info();}
+	public Db_conn_props_mgr	Props()					{return engine.Props();}
+	public Db_batch_mgr			Batch_mgr()				{return engine.Batch_mgr();}
+	public Db_engine			Engine()				{return engine;} private final    Db_engine engine;
+	public Db_sys_mgr			Sys_mgr()				{return sys_mgr;} private final    Db_sys_mgr sys_mgr;	// autonum and other functions
+	public boolean				Eq(Db_conn comp)		{return String_.Eq(engine.Conn_info().Db_api(), comp.Conn_info().Db_api());}
+	public void					Txn_bgn(String name)	{engine.Txn_bgn(name);}
+	public void					Txn_end()				{engine.Txn_end();}
+	public void					Txn_cxl()				{engine.Txn_cxl();}
+	public void					Txn_sav()				{engine.Txn_sav();}
+	public void					Env_db_attach(String alias, Db_conn conn)										{engine.Env_db_attach(alias, conn);}
+	public void					Env_db_attach(String alias, Io_url db_url)										{engine.Env_db_attach(alias, db_url);}
+	public void					Env_db_detach(String alias)														{engine.Env_db_detach(alias);}
+	public void					Env_vacuum()																	{Exec_sql_plog_ntx("vacuuming: url=" + this.Conn_info().Db_api(), "VACUUM;");}
+	public void					Meta_tbl_create(Dbmeta_tbl_itm meta)											{engine.Meta_tbl_create(meta); engine.Meta_idx_create(Gfo_usr_dlg_.Noop, meta.Idxs().To_ary());}
+	public void					Meta_tbl_delete(String tbl)														{engine.Meta_tbl_delete(tbl);}
+	public void					Meta_tbl_remake_many(Db_tbl... tbls)										{for (Db_tbl tbl : tbls) Meta_tbl_remake(tbl);}
+	public void					Meta_tbl_remake(Db_tbl tbl)														{engine.Meta_tbl_delete(tbl.Tbl_name()); tbl.Create_tbl();}
+	public void					Meta_tbl_remake(Dbmeta_tbl_itm meta)											{engine.Meta_tbl_delete(meta.Name()); engine.Meta_tbl_create(meta);}
+	public void					Meta_idx_assert(String tbl, String suffix, String... flds)				{if (engine.Meta_idx_exists(tbl + "__" + suffix)) return; this.Meta_idx_create(tbl, suffix, flds);}
+	public void					Meta_idx_assert(String tbl, String suffix, Dbmeta_idx_fld... flds)		{if (engine.Meta_idx_exists(tbl + "__" + suffix)) return; this.Meta_idx_create(tbl, suffix, flds);}
+	public void					Meta_idx_create(String tbl, String suffix, String... flds)				{engine.Meta_idx_create(Gfo_usr_dlg_.Instance, Dbmeta_idx_itm.new_normal_by_tbl(tbl, suffix, flds));}
+	public void					Meta_idx_create(String tbl, String suffix, Dbmeta_idx_fld... flds)		{engine.Meta_idx_create(Gfo_usr_dlg_.Instance, Dbmeta_idx_itm.new_normal_by_tbl(tbl, suffix, flds));}
+	public void					Meta_idx_create(Dbmeta_idx_itm... idxs)									{engine.Meta_idx_create(Gfo_usr_dlg_.Instance, idxs);}
+	public void					Meta_idx_create(Gfo_usr_dlg usr_dlg, Dbmeta_idx_itm... idxs)				{engine.Meta_idx_create(usr_dlg, idxs);}
+	public void					Meta_idx_delete(String idx)														{engine.Meta_idx_delete(idx);}
+	public void					Meta_idx_delete(String tbl, String suffix)										{engine.Meta_idx_delete(tbl + "__" + suffix);}
+	public void					Meta_fld_append(String tbl, Dbmeta_fld_itm fld)									{engine.Meta_fld_append(tbl, fld);}
+	public void					Meta_fld_assert(String tbl, String fld, Dbmeta_fld_tid tid, Object dflt)		{if (!Meta_fld_exists(tbl, fld)) this.Meta_fld_append(tbl, new Dbmeta_fld_itm(fld, tid).Default_(dflt));}
+	public boolean				Meta_tbl_exists(String tbl)														{return engine.Meta_tbl_exists(tbl);}
+	public boolean				Meta_fld_exists(String tbl, String fld)											{return engine.Meta_fld_exists(tbl, fld);}
+	public boolean				Meta_idx_exists(String idx)														{return engine.Meta_idx_exists(idx);}
+	public boolean				Meta_idx_exists(String tbl, String suffix)										{return engine.Meta_idx_exists(tbl + "__" + suffix);}
+	public void					Meta_tbl_assert(Db_tbl... tbls) {
+		boolean dirty = false;
+		for (Db_tbl tbl : tbls) {
+			if (!Meta_tbl_exists(tbl.Tbl_name())) {
+				tbl.Create_tbl();
+				dirty = true;
+			}
+		}
+		if (dirty) this.Meta_mgr().Load_all();
+	}
+	public String Meta_fld_append_if_missing(String tbl_name, Dbmeta_fld_list flds, Dbmeta_fld_itm fld) {
+		String fld_name = fld.Name();
+		// if fld doesn't exist, add it; NOTE: need to check if tbl exists first else meta_fld not available
+		if (	this.Meta_tbl_exists(tbl_name)
+			&& !this.Meta_fld_exists(tbl_name, fld_name)) {
+			try {this.Meta_fld_append(tbl_name, fld);}
+			catch (Exception e) {
+				Gfo_log_.Instance.Warn("failed to append fld", "conn", this.Conn_info().Db_api(), "tbl", tbl_name, "fld", fld_name, "err", Err_.Message_gplx_log(e));
+				fld_name = Dbmeta_fld_itm.Key_null;
+			}
+		}
+		// if fld does exist, or tbl doesn't exist, just add fld to collection
+		else {
+			if (!flds.Has(fld.Name()))	// NOTE: need to check if it already exists; DATE:2016-09-22
+				fld_name = flds.Add(fld);
+		}
+		return fld_name;
+	}
+	public Dbmeta_tbl_mgr		Meta_mgr()																		{return engine.Meta_mgr();}
+	public Db_stmt				Stmt_insert(String tbl, Dbmeta_fld_list flds)									{return engine.Stmt_by_qry(Db_qry_insert.new_(tbl, flds.To_str_ary_wo_autonum()));}
+	public Db_stmt				Stmt_insert(String tbl, String... cols)									{return engine.Stmt_by_qry(Db_qry_insert.new_(tbl, cols));}
+	public Db_stmt				Stmt_update(String tbl, String[] where, String... cols)					{return engine.Stmt_by_qry(Db_qry_update.New(tbl, where, cols));}
+	public Db_stmt				Stmt_update_exclude(String tbl, Dbmeta_fld_list flds, String... where)	{return engine.Stmt_by_qry(Db_qry_update.New(tbl, where, flds.To_str_ary_exclude(where)));}
+	public Db_stmt				Stmt_delete(String tbl, String... where)									{return engine.Stmt_by_qry(Db_qry_delete.new_(tbl, where));}
+	public Db_stmt				Stmt_select_all(String tbl, Dbmeta_fld_list flds)								{return engine.Stmt_by_qry(Db_qry__select_in_tbl.new_(tbl, String_.Ary_empty, flds.To_str_ary(), null));}
+	public Db_stmt				Stmt_select(String tbl, String[] cols, String... where)					{return engine.Stmt_by_qry(Db_qry__select_in_tbl.new_(tbl, where, cols, null));}
+	public Db_stmt				Stmt_select(String tbl, Dbmeta_fld_list flds, String... where)			{return engine.Stmt_by_qry(Db_qry__select_in_tbl.new_(tbl, where, flds.To_str_ary(), null));}
+	public Db_stmt				Stmt_select_order(String tbl, Dbmeta_fld_list flds, String[] where, String... orderbys) {return engine.Stmt_by_qry(Db_qry__select_in_tbl.new_(tbl, where, flds.To_str_ary(), orderbys));}
+	public Db_stmt				Stmt_select_order(String tbl, String[] flds, String[] where, String... orderbys) {return engine.Stmt_by_qry(Db_qry__select_in_tbl.new_(tbl, where, flds, orderbys));}
+	public Db_stmt				Stmt_new(Db_qry qry) {return engine.Stmt_by_qry(qry);}
+	public Db_stmt				Stmt_sql(String sql) {return engine.Stmt_by_qry(Db_qry_sql.sql_(sql));}
+	public int					Exec_qry(Db_qry qry)										{return Int_.Cast(engine.Exec_as_obj(qry));}
+	public int					Exec_sql_concat(String... ary)						{return this.Exec_qry(Db_qry_sql.dml_(String_.Concat_lines_nl_skip_last(ary)));}
+	public int					Exec_sql_concat_w_msg(String msg, String... ary)		{Gfo_usr_dlg_.Instance.Plog_many("", "", msg); return Exec_sql_concat(ary);}
+	public int					Exec_sql(String sql)										{return this.Exec_qry(Db_qry_sql.dml_(sql));}
+	public int					Exec_sql(String msg, String sql)							{Gfo_usr_dlg_.Instance.Plog_many("", "", msg); return this.Exec_sql(sql);}
+	public Db_rdr				Exec_rdr(String sql)										{return this.Stmt_sql(sql).Exec_select__rls_auto();}
+	public void					Exec_delete_all(String tbl)									{Stmt_delete(tbl).Exec_delete();}
+	public int					Exec_sql_args(String sql, Object... args)	{return this.Exec_qry(Db_qry_sql.dml_(String_.Format(sql, args)));}
+	public int					Exec_sql_plog_ntx(String msg, String sql) {return Exec_sql_plog(Bool_.N, msg, sql);}
+	public int					Exec_sql_plog_txn(String msg, String sql) {return Exec_sql_plog(Bool_.Y, msg, sql);}
+	public int					Exec_sql_plog(boolean txn, String msg, String sql) {			
+		Gfo_usr_dlg_.Instance.Plog_many("", "", msg);
+		if (txn) this.Txn_bgn(msg);
+		int rv = Exec_sql(sql);
+		if (txn) this.Txn_end();
+		Gfo_usr_dlg_.Instance.Plog_many("", "", "done:" + msg);
+		return rv;
+	}
+	public int					Exec_select_max_as_int	(String tbl_name, String fld_name, int or) {
+		Object rv = Exec_select_as_obj(String_.Format("SELECT Max({0}) FROM {1}", fld_name, tbl_name));
+		return rv == null ? or : Int_.Cast(rv);
+	}
+	public int					Exec_select_count_as_int(String tbl_name, int or) {
+		Object rv = Exec_select_as_obj(String_.Format("SELECT Count(*) FROM {0}", tbl_name));
+		return rv == null ? or : Int_.Cast(rv);
+	}
+	public int					Exec_select_as_int		(String sql, int    or) {Object rv = Exec_select_as_obj(sql); return rv == null ? or : Int_.Cast(rv);}
+	public double				Exec_select_as_double	(String sql, double or) {Object rv = Exec_select_as_obj(sql); return rv == null ? or : Double_.cast(rv);}
+	private Object				Exec_select_as_obj(String sql) {
+		Db_rdr rdr = Exec_rdr(sql);
+		try {return rdr.Move_next() ? rdr.Read_at(0) : null;}
+		finally {rdr.Rls();}
+	}
+	public void					Rls_reg(Rls_able rls) {
+		if (this == Db_conn_.Noop) return;	// ignore Db_conn_.Noop, else memory leak
+		rls_list.Add(rls);
+	}
+	public void					Rls_conn() {
+		int len = rls_list.Count();
+		for (int i = 0; i < len; ++i) {
+			Rls_able itm = (Rls_able)rls_list.Get_at(i);
+			itm.Rls();
+		}
+		// rls_list.Clear(); // TOMBSTONE: do not clear rls_list, else tables which self-registered won't get called again; DATE:2016-07-06
+		engine.Conn_term();
+		Db_conn_pool.Instance.Del(engine.Conn_info());
+	}
+	public void Reopen_conn() {
+		engine.Conn_open();
+		Db_conn_pool.Instance.Add_existing(this);
+	}
+	public Db_stmt				Stmt_select_max(String tbl, String col, String... where) {
+		Db_qry__select_in_tbl qry = new Db_qry__select_in_tbl(tbl, String_.Ary(String_.Format("Max({0}) AS {0}", col)), where, null, null, null, null);
+		qry.Where_(where.length == 0 ? Db_crt_.Wildcard : Db_crt_.eq_many_(where));
+		return engine.Stmt_by_qry(qry);
+	}
+
+	public DataRdr				Exec_sql_as_old_rdr(String sql)		{return DataRdr_.cast(engine.Exec_as_obj(Db_qry_sql.rdr_(sql)));}
+	public DataRdr				Exec_qry_as_old_rdr(Db_qry qry)		{return DataRdr_.cast(engine.Exec_as_obj(qry));}
+}

140_dbs/src/gplx/dbs/Db_conn_.java

@@ -0,0 +1,19 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+public class Db_conn_ {
+	public static final    Db_conn Noop = new Db_conn(gplx.dbs.engines.noops.Noop_engine.Instance);
+}

140_dbs/src/gplx/dbs/Db_conn_bldr.java

@@ -0,0 +1,52 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+public class Db_conn_bldr {
+	private final    Object thread_lock = new Object();	// LOCK:synchronized else random failures in Schema_mgr due to diff conn pointing to same db; DATE:2016-07-12
+	private Db_conn_bldr_wkr wkr;
+	public void Reg_default_sqlite()	{wkr = Db_conn_bldr_wkr__sqlite.Instance; wkr.Clear_for_tests();}
+	public void Reg_default_mem()		{wkr = Db_conn_bldr_wkr__mem.Instance; wkr.Clear_for_tests();}
+	public boolean Exists(Io_url url) {synchronized (thread_lock) {return wkr.Exists(url);}}
+	public Db_conn Get(Io_url url) {synchronized (thread_lock) {return wkr.Get(url);}}
+	public Db_conn New(Io_url url) {synchronized (thread_lock) {return wkr.New(url);}}
+	public Db_conn_bldr_data Get_or_new(Io_url url) {
+		synchronized (thread_lock) {
+			boolean exists = wkr.Exists(url);
+			Db_conn conn = exists ? Get(url) : New(url);
+			return new Db_conn_bldr_data(conn, exists);
+		}
+	}
+	public Db_conn Get_or_noop(Io_url url) {
+		synchronized (thread_lock) {
+			Db_conn rv = wkr.Get(url);
+			return rv == null ? Db_conn_.Noop : rv;
+		}
+	}
+	public Db_conn Get_or_autocreate(boolean autocreate, Io_url url) {
+		synchronized (thread_lock) {
+			boolean exists = wkr.Exists(url);
+			if (exists) return Get(url);
+			if (autocreate) return New(url);
+			else throw Err_.new_("dbs", "db does not exist", "url", url.Raw());
+		}
+	}
+	public Db_conn Get_or_fail(Io_url url) {
+		Db_conn rv = Get(url);
+		if (rv == Db_conn_.Noop) throw Err_.new_wo_type("connection is null; file does not exist: file={0}", "file", url.Raw());
+		return rv;
+	}
+        public static final    Db_conn_bldr Instance = new Db_conn_bldr(); Db_conn_bldr() {}
+}

140_dbs/src/gplx/dbs/Db_conn_bldr_data.java

@@ -0,0 +1,22 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+public class Db_conn_bldr_data {
+	public Db_conn_bldr_data(Db_conn conn, boolean exists) {this.conn = conn; this.exists = exists;}
+	public Db_conn Conn() {return conn;} private final Db_conn conn;
+	public boolean Exists() {return exists;} private final boolean exists;
+	public boolean Created() {return !exists;}
+}

140_dbs/src/gplx/dbs/Db_conn_bldr_wkr.java

@@ -0,0 +1,63 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+import gplx.dbs.engines.sqlite.*; import gplx.dbs.qrys.bats.*;
+public interface Db_conn_bldr_wkr {
+	void Clear_for_tests();
+	boolean Exists(Io_url url);
+	Db_conn Get(Io_url url);
+	Db_conn New(Io_url url);
+}
+class Db_conn_bldr_wkr__sqlite implements Db_conn_bldr_wkr {
+	public void Clear_for_tests() {}
+//		public Db_batch_mgr Batch_mgr() {return batch_mgr;} private final    Db_batch_mgr batch_mgr = new Db_batch_mgr();
+	public boolean Exists(Io_url url) {return Io_mgr.Instance.ExistsFil(url);}
+	public Db_conn Get(Io_url url) {
+		if (!Io_mgr.Instance.ExistsFil(url)) return null;
+		Db_conn_info db_url = Db_conn_info_.sqlite_(url);
+		return Db_conn_pool.Instance.Get_or_new(db_url);
+	}
+	public Db_conn New(Io_url url) {
+		Io_mgr.Instance.CreateDirIfAbsent(url.OwnerDir());	// must assert that dir exists
+		Db_conn_info db_url = Sqlite_conn_info.make_(url);
+		Db_conn conn = Db_conn_pool.Instance.Get_or_new(db_url);
+		conn.Exec_qry(Sqlite_pragma.New__page_size(4096));
+		return conn;
+	}
+        public static final    Db_conn_bldr_wkr__sqlite Instance = new Db_conn_bldr_wkr__sqlite(); Db_conn_bldr_wkr__sqlite() {}
+}
+class Db_conn_bldr_wkr__mem implements Db_conn_bldr_wkr {
+	private final    Hash_adp hash = Hash_adp_.New();
+	public void Clear_for_tests() {hash.Clear(); Db_conn_pool.Instance.Rls_all();}
+	public boolean Exists(Io_url url) {
+		String io_url_str = url.Xto_api();
+		return hash.Has(io_url_str);
+	}
+	public Db_conn Get(Io_url url) {
+		String io_url_str = url.Xto_api();
+		if (!hash.Has(io_url_str)) return null;
+		return Get_or_new(url);
+	}
+	public Db_conn New(Io_url url) {
+		String io_url_str = url.Xto_api();
+		hash.Add_if_dupe_use_nth(io_url_str, io_url_str);	// NOTE: tests can call New multiple times; don't fail if exists; just overwrite existing entry; DATE:2016-04-21
+		return Get_or_new(url);
+	}
+	private Db_conn Get_or_new(Io_url url) {
+		return Db_conn_pool.Instance.Get_or_new(gplx.dbs.engines.mems.Mem_conn_info.new_(url.Xto_api()));
+	}
+        public static final    Db_conn_bldr_wkr__mem Instance = new Db_conn_bldr_wkr__mem(); Db_conn_bldr_wkr__mem() {}
+}

140_dbs/src/gplx/dbs/Db_conn_info.java

@@ -0,0 +1,23 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+public interface Db_conn_info {
+	String Key();				// EX: "sqlite"
+	String Raw();				// EX: "gplx_key=sqlite;data source=/db.sqlite3;version=3"
+	String Db_api();			// EX: "data source=/db.sqlite3;version=3"
+	String Database();			// EX: /db.sqlite3 -> "db" ; xowa -> "xowa"
+	Db_conn_info New_self(String raw, Keyval_hash hash);
+}

140_dbs/src/gplx/dbs/Db_conn_info_.java

@@ -0,0 +1,86 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+import gplx.dbs.engines.noops.*; import gplx.dbs.engines.mems.*; import gplx.dbs.engines.sqlite.*; import gplx.dbs.engines.tdbs.*;
+import gplx.dbs.engines.mysql.*; import gplx.dbs.engines.postgres.*;
+public class Db_conn_info_ {
+	public static final    Db_conn_info Null			= Noop_conn_info.Instance;
+	public static final    Db_conn_info Test			= Mysql_conn_info.new_("127.0.0.1", "unit_tests", "root", "mysql7760");
+	public static Db_conn_info parse(String raw)		{return Db_conn_info_pool.Instance.Parse(raw);}
+	public static Db_conn_info sqlite_(Io_url url)		{return Sqlite_conn_info.load_(url);}
+	public static Db_conn_info tdb_(Io_url url)			{return Tdb_conn_info.new_(url);}
+	public static Db_conn_info mem_(String db)			{return Mem_conn_info.new_(db);}
+	public static final    String Key_tdb = Tdb_conn_info.Tid_const;
+	public static Io_url To_url(Db_conn_info cs) {
+		if		(String_.Eq(cs.Key(), Sqlite_conn_info.Key_const))		return ((Sqlite_conn_info)cs).Url();
+		else if (String_.Eq(cs.Key(), Mem_conn_info.Instance.Key()))	return Io_url_.mem_fil_("mem/" + ((Mem_conn_info)cs).Database());
+		else throw Err_.new_unhandled_default(cs.Key());
+	}
+}
+class Db_conn_info_pool {
+	private final    Ordered_hash regy = Ordered_hash_.New();
+	public Db_conn_info_pool() {
+		this.Add(Noop_conn_info.Instance).Add(Tdb_conn_info.Instance).Add(Mysql_conn_info.Instance).Add(Postgres_conn_info.Instance).Add(Sqlite_conn_info.Instance);
+		this.Add(Mem_conn_info.Instance);
+	}
+	public Db_conn_info_pool Add(Db_conn_info itm) {regy.Add_if_dupe_use_nth(itm.Key(), itm); return this;}
+	public Db_conn_info Parse(String raw) {// assume each pair has format of: name=val;
+		try {
+			Keyval_hash hash = new Keyval_hash();
+			String[] terms = String_.Split(raw, ";");
+			String url_tid = "";
+			for (String term : terms) {
+				if (String_.Len(term) == 0) continue;
+				String[] kv = String_.Split(term, "=");
+				if (String_.Eq(kv[0], "gplx_key"))
+					url_tid = kv[1]; // NOTE: do not add to GfoMsg; will not be part of ApiStr
+				else
+					hash.Add(kv[0], kv[1]);
+			}
+			Db_conn_info prototype = (Db_conn_info)regy.Get_by(url_tid);
+			return prototype.New_self(raw, hash);
+		}
+		catch(Exception exc) {throw Err_.new_parse_exc(exc, Db_conn_info.class, raw);}
+	}
+	public Db_conn_info Parse_or_sqlite_or_fail(String raw) {// assume each pair has format of: name=val;
+		Keyval_hash hash = new Keyval_hash();
+		String[] kvps = String_.Split(raw, ";");
+		String cs_tid = null;
+		int kvps_len = kvps.length; 
+		for (int i = 0; i < kvps_len; ++i) {
+			String kvp_str = kvps[i];
+			if (String_.Len(kvp_str) == 0) continue;	// ignore empty; EX: "data source=/db.sqlite;;"
+			String[] kvp = String_.Split(kvp_str, "=");
+			String key = kvp[0], val = kvp[1];
+			if (String_.Eq(key, "gplx_key"))
+				cs_tid = val;	// NOTE: do not add to GfoMsg; will not be part of ApiStr
+			else
+				hash.Add(key, val);
+		}
+		if (cs_tid == null) {	// gplx_key not found; try url as sqlite; EX: "/db.sqlite"
+			Io_url sqlite_url = null;
+			try {sqlite_url = Io_url_.new_any_(raw);}
+			catch (Exception exc) {throw Err_.new_exc(exc, "dbs", "invalid connection String", "raw", raw);}
+			hash.Clear();
+			cs_tid = Sqlite_conn_info.Key_const;
+			hash.Add(Sqlite_conn_info.Cs__data_source, sqlite_url.Raw());
+			hash.Add(Sqlite_conn_info.Cs__version	, Sqlite_conn_info.Cs__version__3);
+		}
+		Db_conn_info prototype = (Db_conn_info)regy.Get_by(cs_tid);
+		return prototype.New_self(raw, hash);
+	}
+	public static final    Db_conn_info_pool Instance = new Db_conn_info_pool();
+}

140_dbs/src/gplx/dbs/Db_conn_info__base.java

@@ -0,0 +1,48 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+public abstract class Db_conn_info__base implements Db_conn_info {
+	public Db_conn_info__base(String raw, String db_api, String database) {this.raw = raw; this.db_api = db_api; this.database = database;}
+	public abstract String Key();
+	public String Raw()				{return raw;} private final    String raw;
+	public String Db_api()			{return db_api;} private final    String db_api;
+	public String Database()		{return database;} protected final    String database;
+	public abstract Db_conn_info New_self(String raw, Keyval_hash hash);
+
+	protected static String Bld_raw(String... ary) {// "a", "b" -> "a=b;"
+		Bry_bfr bfr = Bry_bfr_.Reset(255);
+		int len = ary.length;
+		for (int i = 0; i < len; ++i) {
+			String itm = ary[i];
+			bfr.Add_str_u8(itm);
+			bfr.Add_byte(i % 2 == 0 ? Byte_ascii.Eq : Byte_ascii.Semic);
+		}
+		return bfr.To_str_and_clear();
+	}
+	protected static String Bld_api(Keyval_hash hash, Keyval... xtn_ary) {
+		Bry_bfr bfr = Bry_bfr_.New();
+		int len = hash.Count();
+		for (int i = 0; i < len; ++i) {
+			Keyval kv = hash.Get_at(i);
+			bfr.Add_str_u8_fmt("{0}={1};", kv.Key(), kv.Val_to_str_or_empty());
+		}
+		for (Keyval xtn : xtn_ary) {
+			if (hash.Has(xtn.Key())) continue;
+			bfr.Add_str_u8_fmt("{0}={1};", xtn.Key(), xtn.Val_to_str_or_empty());
+		}
+		return bfr.To_str_and_clear();
+	}
+}

140_dbs/src/gplx/dbs/Db_conn_info_tst.java

@@ -0,0 +1,46 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+import org.junit.*;
+public class Db_conn_info_tst {
+	@Before public void setup() {
+		regy.Add(Db_conn_info_mock.Instance);
+	}	private final Db_conn_info_pool regy = new Db_conn_info_pool();
+	@Test  public void Parse() {
+		tst_Parse("gplx_key=mock;id=1;", kv_("id", "1"));							 // one; gplx_key removed
+		tst_Parse("gplx_key=mock;id=1;name=me;", kv_("id", "1"), kv_("name", "me")); // many
+		tst_Parse("gplx_key=mock;id=1;name=me" , kv_("id", "1"), kv_("name", "me")); // no semi-colon at end
+	}
+	private Keyval kv_(String key, Object val) {return Keyval_.new_(key, val);}
+	private void tst_Parse(String raw, Keyval... expd) {
+		Db_conn_info_mock mock = (Db_conn_info_mock)regy.Parse(raw);
+		Tfds.Eq_ary_str(expd, mock.Kvs());
+	}
+}
+class Db_conn_info_mock extends Db_conn_info__base {
+	public Db_conn_info_mock(String raw, String db_api, String database) {super(raw, db_api, database);}
+	public Keyval[] Kvs() {return kvs;} Keyval[] kvs;
+	@Override public String Key() {return Tid_const;} public static final String Tid_const = "mock";
+	@Override public Db_conn_info New_self(String raw, Keyval_hash hash) {
+		Db_conn_info_mock rv = new Db_conn_info_mock("", "", "");
+		int len = hash.Count();
+		rv.kvs = new Keyval[len];
+		for (int i = 0; i < len; ++i)
+			rv.kvs[i] = hash.Get_at(i);
+		return rv;
+	}
+        public static final Db_conn_info_mock Instance = new Db_conn_info_mock("", "", "");
+}

140_dbs/src/gplx/dbs/Db_conn_pool.java

@@ -0,0 +1,64 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+import gplx.dbs.engines.*;
+import gplx.dbs.qrys.bats.*;
+public class Db_conn_pool {	// PURPOSE: cache one connection per connection_string
+	private final    Ordered_hash hash = Ordered_hash_.New();
+	public Db_batch_mgr Batch_mgr() {return batch_mgr;} private final    Db_batch_mgr batch_mgr = new Db_batch_mgr();
+	public void Del(Db_conn_info url)				{hash.Del(url.Db_api());}
+	public Db_conn Get_or_new(String s)				{return Get_or_new(Db_conn_info_.parse(s));}
+	public Db_conn Get_or_new(Db_conn_info url) {
+		Db_conn rv = (Db_conn)hash.Get_by(url.Db_api());
+		if (rv == null) {
+			Db_engine prime = (Db_engine)prime_hash.Get_by(url.Key()); if (prime == null) Err_.new_wo_type("db engine prototype not found", "key", url.Key());
+			Db_engine clone = prime.New_clone(url);
+			rv = new Db_conn(clone);
+			clone.Batch_mgr().Copy(clone.Tid(), batch_mgr);
+			hash.Add(url.Db_api(), rv);
+		}
+		return rv;
+	}
+	public void Add_existing(Db_conn conn) {
+		hash.Add(conn.Conn_info().Db_api(), conn);
+	}
+	public void Rls_all() {
+		int len = hash.Len();
+		Db_conn[] rls_ary = new Db_conn[len];
+		for (int i = 0; i < len; ++i)
+			rls_ary[i] = (Db_conn)hash.Get_at(i);
+		for (int i = 0; i < len; ++i)
+			rls_ary[i].Rls_conn();
+		hash.Clear();
+	}
+
+	private final    Hash_adp prime_hash = Hash_adp_.New();
+        public static final    Db_conn_pool Instance = new Db_conn_pool(); Db_conn_pool() {this.Init();}
+	public void Primes__add(Db_engine... ary) {	// PUBLIC.DRD:
+		for (Db_engine itm : ary)
+			prime_hash.Add(itm.Tid(), itm);
+	}
+	private void Init() {
+		this.Primes__add
+		( gplx.dbs.engines.noops	.Noop_engine.Instance
+		, gplx.dbs.engines.mems		.Mem_engine.Instance
+		, gplx.dbs.engines.sqlite	.Sqlite_engine.Instance
+		, gplx.dbs.engines.mysql	.Mysql_engine.Instance
+		, gplx.dbs.engines.postgres	.Postgres_engine.Instance
+		, gplx.dbs.engines.tdbs		.TdbEngine.Instance
+		);
+	}
+}

140_dbs/src/gplx/dbs/Db_conn_utl.java

@@ -0,0 +1,75 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+import gplx.dbs.metas.*;
+public class Db_conn_utl {
+	public static Db_conn Conn__new(String url_rel) {
+		Db_conn_bldr.Instance.Reg_default_mem();
+		return Db_conn_bldr.Instance.Get_or_new(Io_url_.mem_fil_("mem/" + url_rel)).Conn();
+	}
+	public static void Tbl__new(Db_conn conn, String tbl, Dbmeta_fld_itm[] flds, Object[]... rows) {
+		conn.Meta_tbl_create(Dbmeta_tbl_itm.New(tbl, flds));
+		int rows_len = rows.length;
+		Db_stmt stmt = conn.Stmt_insert(tbl, Dbmeta_fld_itm.To_str_ary(flds));
+		for (int i = 0; i < rows_len; ++i) {
+			Object[] row = rows[i];
+			int dat_len = row.length;
+			stmt.Clear();
+			for (int j = 0; j < dat_len; ++j) {
+				Dbmeta_fld_itm fld = flds[j];
+				String fld_name = fld.Name();
+				Object val = row[j];
+				switch (fld.Type().Tid_ansi()) {
+					case Dbmeta_fld_tid.Tid__bool:		stmt.Val_bool_as_byte	(fld_name, Bool_.Cast(val)); break;
+					case Dbmeta_fld_tid.Tid__byte:		stmt.Val_byte			(fld_name, Byte_.Cast(val)); break;
+					case Dbmeta_fld_tid.Tid__int:		stmt.Val_int			(fld_name, Int_.Cast(val)); break;
+					case Dbmeta_fld_tid.Tid__long:		stmt.Val_long			(fld_name, Long_.cast(val)); break;
+					case Dbmeta_fld_tid.Tid__float:		stmt.Val_float			(fld_name, Float_.cast(val)); break;
+					case Dbmeta_fld_tid.Tid__double:	stmt.Val_double			(fld_name, Double_.cast(val)); break;
+					case Dbmeta_fld_tid.Tid__str:		stmt.Val_str			(fld_name, String_.cast(val)); break;
+					case Dbmeta_fld_tid.Tid__bry:		stmt.Val_bry			(fld_name, Bry_.cast(val)); break;
+				}
+			}
+			stmt.Exec_insert();
+		}
+	}
+	public static void Insert(Db_conn conn, String tbl_name, String[] flds, Object[]... rows) {
+		Db_stmt stmt = Db_stmt_.new_insert_(conn, tbl_name, flds);
+		int flds_len = flds.length;
+		int rows_len = rows.length;
+		for (int i = 0; i < rows_len; ++i) {
+			Object[] row = rows[i];
+			stmt.Clear();
+			for (int j = 0; j < flds_len; ++j)
+				Db_stmt_.Val_by_obj(stmt, flds[j], row[j]);
+			stmt.Exec_insert();
+		}
+	}
+	public static Object[][] Select(Db_conn conn, Db_qry qry) {
+		List_adp rv = List_adp_.New();
+		Db_rdr rdr = conn.Stmt_new(qry).Exec_select__rls_auto();
+		try {
+			while (rdr.Move_next()) {
+				int fld_len = rdr.Fld_len();
+				Object[] row = new Object[fld_len];
+				for (int i = 0; i < fld_len; ++i)
+					row[i] = rdr.Read_at(i);
+				rv.Add(row);
+			}
+		}	finally {rdr.Rls();}
+		return (Object[][])rv.To_ary_and_clear(Object[].class);
+	}
+}

140_dbs/src/gplx/dbs/Db_crt_.java

@@ -0,0 +1,63 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+import gplx.core.criterias.*;
+public class Db_crt_ {
+	public static final Criteria Wildcard = Criteria_.All;
+	public static Criteria     New_and			(Criteria lhs, Criteria rhs)					{return Criteria_.And(lhs, rhs);}
+	public static Criteria_fld New_eq			(String key, Object val)						{return Criteria_fld.new_(key, Criteria_.eq_(val));}
+	public static Criteria_fld New_eq			(String pre, String key, Object val)			{return Criteria_fld.new_(pre, key, Criteria_.eq_(val));}
+	public static Criteria_fld New_eq_not		(String key, Object val)						{return Criteria_fld.new_(key, Criteria_.eqn_(val));}
+	public static Criteria_fld New_lt			(String key, Comparable val)					{return Criteria_fld.new_(key, Criteria_.lt_(val));}
+	public static Criteria_fld New_lte			(String key, Comparable val)					{return Criteria_fld.new_(key, Criteria_.lte_(val));}
+	public static Criteria_fld New_mt			(String key, Comparable val)					{return Criteria_fld.new_(key, Criteria_.mt_(val));}
+	public static Criteria_fld New_mte			(String key, Comparable val)					{return Criteria_fld.new_(key, Criteria_.mte_(val));}
+	public static Criteria_fld New_between		(String key, Comparable lo, Comparable hi)	{return Criteria_fld.new_(key, Criteria_.between_(lo, hi));}
+	public static Criteria_fld New_in			(String key, Object... vals)				{return Criteria_fld.new_(key, Criteria_.in_(vals));}
+	public static Criteria_fld New_like			(String key, String pattern)					{return Criteria_fld.new_(key, Criteria_.like_(pattern));}
+
+	public static Criteria eq_many_(String... ary) {
+		Criteria rv = null;
+		int len = ary.length;
+		for (int i = 0; i < len; i++) {
+			Criteria crt = Db_crt_.New_eq(ary[i], null);
+			rv = (i == 0)? crt : Criteria_.And(rv, crt);
+		}
+		return rv;
+	}
+	public static Criteria eq_many_wo_null(String... ary) {
+		Criteria rv = null;
+		int len = ary.length;
+		int crt_idx = 0;
+		for (int i = 0; i < len; i++) {
+			String itm = ary[i]; if (itm == Dbmeta_fld_itm.Key_null) continue;
+			Criteria crt = Db_crt_.New_eq(itm, null);
+			rv = (crt_idx == 0) ? crt : Criteria_.And(rv, crt);
+			++crt_idx;
+		}
+		return rv;
+	}
+	public static Criteria eq_many_(Keyval... array) {
+		Criteria rv = null;
+		for (int i = 0; i < array.length; i++) {
+			Keyval pair = array[i];
+			Criteria crt = Db_crt_.New_eq(pair.Key(), pair.Val());
+			rv = (i == 0)? crt : Criteria_.And(rv, crt);
+		}
+		return rv;
+	}
+	public static Criteria_fld wrap_(String key, Criteria crt) {return Criteria_fld.new_(key, crt);}
+}

140_dbs/src/gplx/dbs/Db_crt_tst.java

@@ -0,0 +1,50 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+import org.junit.*; import gplx.core.criterias.*; import gplx.core.gfo_ndes.*; import gplx.core.type_xtns.*;
+public class Db_crt_tst {
+	@Before public void setup() {
+		row = GfoNde_.vals_(GfoFldList_.new_().Add("id", IntClassXtn.Instance).Add("name", StringClassXtn.Instance), Object_.Ary(1, "me"));
+	}
+	@Test  public void EqualTest() {
+		crt = Db_crt_.New_eq("id", 1);
+		tst_Match(true, row, crt);
+	}
+	@Test  public void EqualFalseTest() {
+		crt = Db_crt_.New_eq("id", 2);
+		tst_Match(false, row, crt);
+	}
+	@Test  public void AndCompositeTest() {
+		crt = Criteria_.And(Db_crt_.New_eq("id", 1), Db_crt_.New_eq("name", "me"));
+		tst_Match(true, row, crt);
+
+		crt = Criteria_.And(Db_crt_.New_eq("id", 1), Db_crt_.New_eq("name", "you"));
+		tst_Match(false, row, crt);
+	}
+	@Test  public void OrCompositeTest() {
+		crt = Criteria_.Or(Db_crt_.New_eq("id", 1), Db_crt_.New_eq("name", "you"));
+		tst_Match(true, row, crt);
+
+		crt = Criteria_.Or(Db_crt_.New_eq("id", 2), Db_crt_.New_eq("name", "you"));
+		tst_Match(false, row, crt);
+	}
+
+	void tst_Match(boolean epxd, GfoNde row, Criteria crt) {
+		boolean actl = crt.Matches(row);
+		Tfds.Eq(epxd, actl);
+	}
+	GfoNde row; Criteria crt;
+}

140_dbs/src/gplx/dbs/Db_idx_itm.java

@@ -0,0 +1,32 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+public class Db_idx_itm {
+	public String Xto_sql() {return sql;} private String sql;
+	public static Db_idx_itm sql_(String sql) {
+		Db_idx_itm rv = new Db_idx_itm();
+		rv.sql = sql;
+		return rv;
+	}
+	public static Db_idx_itm[] ary_sql_(String... ary) {
+		int len = ary.length;
+		Db_idx_itm[] rv = new Db_idx_itm[len];
+		for (int i = 0; i < len; i++) {
+			rv[i] = sql_(ary[i]);
+		}
+		return rv;
+	}
+}

140_dbs/src/gplx/dbs/Db_mock_cell.java

@@ -0,0 +1,22 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+public class Db_mock_cell {
+	public int Idx() {return idx;} public Db_mock_cell Idx_(int val) {idx = val; return this;} int idx = -1;
+	public String Fld() {return fld;} public Db_mock_cell Fld_(String v) {fld = v; return this;} private String fld = null;
+	public Object Val() {return val;} public Db_mock_cell Val_(Object v) {val = v; return this;} Object val = null;
+	public static Db_mock_cell new_() {return new Db_mock_cell();} Db_mock_cell() {}
+}

140_dbs/src/gplx/dbs/Db_mock_row.java

@@ -0,0 +1,29 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+public class Db_mock_row {
+	public int Idx() {return idx;} public Db_mock_row Idx_(int val) {idx = val; return this;} int idx = -1;
+	public Db_mock_cell[] Dat() {return dat;} Db_mock_cell[] dat = null;
+	public static Db_mock_row vals_only_(Object... ary) {
+		Db_mock_row rv = new Db_mock_row();
+		int len = Array_.Len(ary);
+		rv.dat = new Db_mock_cell[len];
+		for (int i = 0; i < len; i++)
+			rv.dat[i] = Db_mock_cell.new_().Val_(ary[i]);
+		return rv;
+	}
+	public static Db_mock_row new_() {return new Db_mock_row();} Db_mock_row() {}
+}

140_dbs/src/gplx/dbs/Db_null.java

@@ -0,0 +1,22 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+public class Db_null implements gplx.core.brys.Bfr_arg {
+	public void Bfr_arg__add(Bry_bfr bfr) {bfr.Add_str_a7(Null_str);}
+	@Override public String toString() {return Null_str;}
+	public static final String Null_str = "NULL";
+        public static final Db_null Instance = new Db_null(); Db_null() {}
+}

140_dbs/src/gplx/dbs/Db_qry.java

@@ -0,0 +1,28 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+public interface Db_qry {
+	int			Tid();
+	boolean		Exec_is_rdr();
+	String		Base_table();
+	String		To_sql__exec(gplx.dbs.sqls.Sql_qry_wtr wtr);
+}
+class Db_qry__noop implements Db_qry {
+	public int	Tid() {return Db_qry_.Tid_noop;}
+	public boolean	Exec_is_rdr() {return false;}
+	public String Base_table() {return "";}
+	public String To_sql__exec(gplx.dbs.sqls.Sql_qry_wtr wtr) {return "";}
+}

140_dbs/src/gplx/dbs/Db_qry_.java

@@ -0,0 +1,61 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+import gplx.core.criterias.*; import gplx.dbs.qrys.*; import gplx.dbs.sqls.*; import gplx.dbs.sqls.itms.*;
+public class Db_qry_ {
+	public static Db_qry__select_cmd select_cols_(String tbl, Criteria crt, String... cols){return select_().From_(tbl).Where_(crt).Cols_(cols);}
+	public static Db_qry__select_cmd select_val_(String tbl, String col, Criteria crt)		{return select_().From_(tbl).Where_(crt).Cols_(col);}
+	public static Db_qry__select_cmd select_tbl_(String tbl)								{return select_().From_(tbl).Cols_all_();}
+	public static Db_qry__select_cmd select_()												{return new Db_qry__select_cmd();}
+	public static Db_qry__select_cmd select_(String tbl, String... cols)				{return new Db_qry__select_cmd().From_(tbl).Cols_(cols);}
+	public static Db_qry_delete delete_(String tbl, Criteria crt)							{return Db_qry_delete.new_(tbl, crt);}
+	public static Db_qry_delete delete_tbl_(String tbl)										{return Db_qry_delete.new_(tbl);}
+	public static Db_qry_insert insert_(String tbl)											{return new Db_qry_insert(tbl);}
+	public static Db_qry_insert insert_common_(String tbl, Keyval... pairs) {
+		Db_qry_insert cmd = new Db_qry_insert(tbl);
+		for (Keyval pair : pairs)
+			cmd.Val_obj(pair.Key(), pair.Val());
+		return cmd;
+	}
+
+	public static Sql_join_fld New_join__join(String trg_fld, String src_tbl, String src_fld)	{return new Sql_join_fld(trg_fld, src_tbl, src_fld);}
+	public static Sql_join_fld New_join__same(String tbl, String fld)							{return new Sql_join_fld(fld, tbl, fld);}
+
+	public static Db_qry_update update_(String tbl, Criteria crt) {
+		Db_qry_update update = new Db_qry_update();
+		update.From_(tbl);
+		update.Where_(crt);
+		return update;
+	}
+	public static Db_qry_update update_common_(String tbl, Criteria crt, Keyval... pairs) {
+		Db_qry_update cmd = new Db_qry_update();
+		cmd.From_(tbl); cmd.Where_(crt);
+		for (Keyval pair : pairs)
+			cmd.Val_obj(pair.Key(), pair.Val());
+		return cmd;
+	}
+	public static gplx.core.gfo_ndes.GfoNde Exec_as_nde(Db_conn conn, Db_qry qry) {return gplx.core.gfo_ndes.GfoNde_.rdr_(conn.Exec_qry_as_old_rdr(qry));}
+	public static Object Exec_as_obj(Db_conn conn, Db_qry__select_cmd qry) {
+		gplx.core.stores.DataRdr rdr = conn.Exec_qry_as_old_rdr(qry);
+		try {
+			return rdr.MoveNextPeer() ? rdr.Read(qry.Cols().Flds.Get_at(0).Fld) : null;	// NOTE: need to access from flds for tdb
+		}	finally {rdr.Rls();}
+	}
+
+	public static Db_qry as_(Object obj) {return obj instanceof Db_qry ? (Db_qry)obj : null;}
+        public static final    Db_qry Noop = new Db_qry__noop();
+	public static final int Tid_insert = 0, Tid_delete = 1, Tid_update = 2, Tid_select = 3, Tid_sql = 4, Tid_select_in_tbl = 5, Tid_flush = 6, Tid_noop = 7, Tid_pragma = 8;
+}

140_dbs/src/gplx/dbs/Db_qry_fxt.java

@@ -0,0 +1,65 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+import gplx.dbs.qrys.*; import gplx.core.gfo_ndes.*;
+public class Db_qry_fxt {
+	public static void Insert_kvo(Db_conn conn, String tblName, Keyval_list kvList) {
+		Db_qry_insert qry = Db_qry_.insert_(tblName);
+		for (int i = 0; i < kvList.Count(); i++) {
+			Keyval kv = kvList.Get_at(i);
+			qry.Val_obj(kv.Key(), kv.Val());
+		}
+		qry.Exec_qry(conn);
+	}
+	public static GfoNde SelectAll(Db_conn conn, String tblName) {
+		return Db_qry_.Exec_as_nde(conn, Db_qry_.select_tbl_(tblName));
+	}
+	public static int SelectAll_count(Db_conn conn, String tblName) {
+		GfoNde nde = Db_qry_fxt.SelectAll(conn, tblName);
+		return nde.Subs().Count();
+	}
+	public static void DeleteAll(Db_conn conn, String... ary) {
+		for (String s : ary)
+			Db_qry_.delete_tbl_(s).Exec_qry(conn);
+	}
+	public static void tst_Select(Db_conn conn, String tblName, Db_mock_row... expdAry) {
+		GfoNde nde = Db_qry_fxt.SelectAll(conn, tblName);
+		int len = Array_.Len(expdAry);
+		for (int i = 0; i < len; i++) {
+			Db_mock_row expdRow = expdAry[i];
+			int actlIdx = (expdRow.Idx() == -1) ? i : expdRow.Idx();
+			GfoNde actlNde = nde.Subs().FetchAt_asGfoNde(actlIdx);
+			int fldLen = Array_.Len(expdRow.Dat());
+			for (int j = 0; j < fldLen; j++) {
+				Db_mock_cell expdDat = expdRow.Dat()[j];
+				Object actlVal = expdDat.Fld() == null ? actlNde.ReadAt(j) : actlNde.Read(expdDat.Fld());
+				Tfds.Eq(expdDat.Val(), actlVal);
+			}
+		}
+	}
+	public static String Db__print_tbl_as_str(Bry_bfr bfr, Db_conn conn, String tbl, String... cols) {
+		int cols_len = cols.length;
+		Db_rdr rdr = conn.Stmt_select(tbl, cols).Exec_select__rls_auto();
+		while (rdr.Move_next()) {
+			for (int i = 0; i < cols_len; ++i) {
+				bfr.Add_obj(rdr.Read_at(i));
+				bfr.Add_byte(i == cols_len - 1 ? Byte_ascii.Nl : Byte_ascii.Pipe);
+			}
+		}
+		rdr.Rls();
+		return bfr.To_str_and_clear();
+	}
+}

140_dbs/src/gplx/dbs/Db_rdr.java

@@ -0,0 +1,34 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+public interface Db_rdr {
+	boolean		Move_next();
+	byte[]		Read_bry(String k);
+	void		Save_bry_in_parts(Io_url url, String tbl, String fld, String crt_key, Object crt_val);
+	byte[]		Read_bry_by_str(String k);
+	String 		Read_str(String k);
+	byte 		Read_byte(String k);
+	int 		Read_int(String k);
+	long 		Read_long(String k);
+	float		Read_float(String k);
+	double		Read_double(String k);
+	DateAdp		Read_date_by_str(String k);
+	boolean		Read_bool_by_byte(String k);
+	int			Fld_len();
+	Object 		Read_obj(String k);
+	Object 		Read_at(int i);
+	void		Rls();
+}

140_dbs/src/gplx/dbs/Db_rdr_.java

@@ -0,0 +1,37 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+public class Db_rdr_ {
+	public static final Db_rdr Empty = new Db_rdr__empty();
+}
+class Db_rdr__empty implements Db_rdr {
+	public boolean			Move_next()						{return false;}
+	public byte[]		Read_bry(String k)				{return Bry_.Empty;}
+	public byte[]		Read_bry_by_str(String k)		{return Bry_.Empty;}
+	public void			Save_bry_in_parts(Io_url url, String tbl, String fld, String crt_key, Object crt_val) {}
+	public byte			Read_byte(String k)				{return Byte_.Max_value_127;}
+	public String 		Read_str(String k)				{return String_.Empty;}
+	public DateAdp		Read_date_by_str(String k)		{return DateAdp_.MinValue;}
+	public int 			Read_int(String k)				{return Int_.Min_value;}
+	public long 		Read_long(String k)				{return Long_.Min_value;}
+	public float		Read_float(String k)			{return Float_.NaN;}
+	public double		Read_double(String k)			{return Double_.NaN;}
+	public boolean			Read_bool_by_byte(String k)		{return false;}
+	public int			Fld_len()						{return 0;}
+	public Object 		Read_obj(String k)				{return null;}
+	public Object 		Read_at(int i)					{return null;}
+	public void			Rls() {}
+}

140_dbs/src/gplx/dbs/Db_rdr__basic.java

@@ -0,0 +1,49 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+import java.sql.ResultSet;
+public class Db_rdr__basic implements Db_rdr {
+	protected ResultSet rdr; 
+	private Db_stmt stmt;
+	public void Ctor(Db_stmt stmt, ResultSet rdr, String sql) {this.stmt = stmt; this.rdr = rdr; this.sql = sql;}  
+	public String		Sql()					{return sql;} private String sql;
+	public boolean			Move_next()	{
+		try	 {return rdr.next();}	
+		catch (Exception e) {throw Err_.new_exc(e, "db", "move_next failed; check column casting error in SQL", "sql", sql);}
+	}
+	@gplx.Virtual public byte[]		Read_bry(String k)			{try {return (byte[])rdr.getObject(k);} catch (Exception e) {throw Err_.new_exc(e, "db", "read failed", "key", k, "type", Bry_.Cls_val_name);}} 
+	@gplx.Virtual public byte[]		Read_bry_by_str(String k)	{try {return Bry_.new_u8((String)rdr.getObject(k));} catch (Exception e) {throw Err_.new_exc(e, "db", "read failed", "key", k, "type", String_.Cls_val_name);}} 
+	@gplx.Virtual public void			Save_bry_in_parts(Io_url url, String tbl, String fld, String crt_key, Object crt_val) {throw Err_.new_unimplemented();}
+	@gplx.Virtual public String 		Read_str(String k)			{try {return (String)rdr.getObject(k);} catch (Exception e) {throw Err_.new_exc(e, "db", "read failed", "key", k, "type", String_.Cls_val_name);}} 
+	@gplx.Virtual public DateAdp		Read_date_by_str(String k)	{return DateAdp_.parse_iso8561(Read_str(k));}
+	@gplx.Virtual public int 			Read_int(String k)			{try {return Int_.Cast(rdr.getObject(k));} catch (Exception e) {throw Err_.new_exc(e, "db", "read failed", "key", k, "type", Int_.Cls_val_name);}} 
+	@gplx.Virtual public long 		Read_long(String k)			{try {return Long_.cast(rdr.getObject(k));} catch (Exception e) {throw Err_.new_exc(e, "db", "read failed", "key", k, "type", Long_.Cls_val_name);}} 
+	@gplx.Virtual public float		Read_float(String k)		{try {return Float_.cast(rdr.getObject(k));} catch (Exception e) {throw Err_.new_exc(e, "db", "read failed", "key", k, "type", Float_.Cls_val_name);}} 
+	@gplx.Virtual public double		Read_double(String k)		{try {return Double_.cast(rdr.getObject(k));} catch (Exception e) {throw Err_.new_exc(e, "db", "read failed", "key", k, "type", Double_.Cls_val_name);}} 
+	@gplx.Virtual public byte			Read_byte(String k)			{try {return Byte_.Cast(rdr.getObject(k));} catch (Exception e) {throw Err_.new_exc(e, "db", "read failed", "key", k, "type", Byte_.Cls_val_name);}} 
+	@gplx.Virtual public boolean 		Read_bool_by_byte(String k)	{try {return Byte_.Cast(rdr.getObject(k)) == 1;} catch (Exception e) {throw Err_.new_exc(e, "db", "read failed", "key", k, "type", Bool_.Cls_val_name);}} 
+	@gplx.Virtual public int			Fld_len()					{try {return rdr.getMetaData().getColumnCount();} catch (Exception e) {throw Err_.new_exc(e, "db", "field count failed", "sql", sql);}}	
+	@gplx.Virtual public Object 		Read_obj(String k)			{try {return rdr.getObject(k);} catch (Exception e) {throw Err_.new_exc(e, "db", "read failed", "key", k, "type", Object_.Cls_val_name);}} 
+	@gplx.Virtual public Object 		Read_at(int i)				{try {return rdr.getObject(i + 1);} catch (Exception e) {throw Err_.new_exc(e, "db", "read failed", "idx", i, "type", Object_.Cls_val_name);}} 
+	@gplx.Virtual public void			Rls() {
+		try	{rdr.close();} 
+		catch (Exception e) {throw Err_.new_exc(e, "db", "close failed");}
+		if (stmt != null) {
+			stmt.Rls();
+			stmt = null;	// NOTE: must null reference else will throw SQLException during statements DATE:2016-04-10
+		}
+	}
+}

140_dbs/src/gplx/dbs/Db_sql_.java

@@ -0,0 +1,60 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+public class Db_sql_ {
+	public static String Make_by_fmt(String[] lines, Object... args) {
+		Bry_bfr bfr = Bry_bfr_.New();
+		int len = lines.length;
+		for (int i = 0; i < len; ++i) {
+			if (i != 0) bfr.Add_byte_nl();
+			bfr.Add_str_u8(lines[i]);
+		}
+		String fmt = bfr.To_str_and_clear();
+		return String_.Format(fmt, args);
+	}
+	public static byte[] Escape_arg(byte[] raw) {
+		int len = raw.length;
+		Bry_bfr bfr = null;
+		boolean dirty = false;
+
+		for (int i = 0; i < len; ++i) {
+			byte b = raw[i];
+			if (b == Byte_ascii.Apos) {
+				if (bfr == null) {
+					dirty = true;
+					bfr = Bry_bfr_.New();
+					bfr.Add_mid(raw, 0, i);
+				}
+				bfr.Add_byte_apos().Add_byte_apos();
+			}
+			else {
+				if (dirty) {
+					bfr.Add_byte(b);
+				}
+			}
+		}
+		return dirty ? bfr.To_bry_and_clear() : raw;
+	}
+	public static String Prep_in_from_ary(Object ary) {	
+		Bry_bfr bfr = Bry_bfr_.New();
+		int len = Array_.Len(ary);
+		for (int i = 0; i < len; i++) {
+			if (i != 0) bfr.Add_byte(Byte_ascii.Comma);
+			bfr.Add_byte(Byte_ascii.Question);
+		}
+		return bfr.To_str_and_clear();
+	}
+}

140_dbs/src/gplx/dbs/Db_sql_select.java

@@ -0,0 +1,76 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+import gplx.core.criterias.*;
+interface Db_sql_qry {
+	String Tbl_main();
+}
+class Db_sql_qry__select {
+	public Db_sql_qry__select(String from) {this.from = from;}
+	public String			From() {return from;} private final    String from;
+	public Db_sql_col[]		Select() {return select;} private Db_sql_col[] select;
+//		public Criteria			Where() {return where;} private Criteria where;
+//		public Db_sql_col[]		Group_bys() {return group_bys;} private Db_sql_col[] group_bys;
+//		public Db_sql_col[]		Order_bys() {return order_bys;} private Db_sql_col[] order_bys;
+//		public int				Limit() {return limit;} private int limit;
+//		public int				Offset() {return offset;} private int offset;
+	public Db_sql_qry__select Select_all_()						{this.select = Db_sql_col_.Ary(new Db_sql_col__all(0, from)); return this;}
+	public Db_sql_qry__select Select_flds_(String... ary)	{this.select = Db_sql_col_bldr.Instance.new_fld_many(ary); return this;}
+	public static Db_sql_qry__select new_(String from) {return new Db_sql_qry__select(from);}
+}
+class Db_sql_bldr {
+	public void Test() {
+//			Db_sql_qry__select qry = null;
+//			qry = Db_sql_qry__select.new_("tbl").Select_all_();
+//			qry = Db_sql_qry__select.new_("tbl").Select_flds_("fld1", "fld2");
+//			qry = Db_sql_qry__select.new_("tbl").Select_flds_("fld1", "fld2").Where_("fld3");
+//				, String_.Ary("col1", "col2"), String_.Ary("col3")).Limit_(10).;
+//			Db_sql_qry__select qry = Db_sql_qry__select_.new_("tbl").Cols_("col1", "col2").Where_eq_one("col3").Limit_(10);
+	}
+}
+interface Db_sql_col {
+	int Ord();
+	String Alias();
+}
+class Db_sql_col_ {
+	public static Db_sql_col[] Ary(Db_sql_col... v) {return v;}
+}
+class Db_sql_col_bldr {
+	private final    List_adp tmp_list = List_adp_.New();
+	public Db_sql_col[] new_fld_many(String[] ary) {
+		tmp_list.Clear();
+		int ord = -1;
+		for (int i = 0; i < ary.length; ++i) {
+			String fld_key = ary[i];
+			if (fld_key == Dbmeta_fld_itm.Key_null) continue;
+			Db_sql_col__name fld = new Db_sql_col__name(++ord, fld_key);
+			tmp_list.Add(fld);
+		}
+		return (Db_sql_col[])tmp_list.To_ary_and_clear(Db_sql_col.class);
+	}
+        public static final    Db_sql_col_bldr Instance = new Db_sql_col_bldr(); Db_sql_col_bldr() {}
+}
+class Db_sql_col__name {
+	public Db_sql_col__name(int ord, String key) {this.ord = ord; this.key = key;}
+	public int Ord() {return ord;} private final    int ord;
+	public String Key() {return key;} private final    String key;
+}
+class Db_sql_col__all implements Db_sql_col {
+	public Db_sql_col__all(int ord, String tbl) {this.ord = ord; this.tbl = tbl;}
+	public int Ord() {return ord;} private final    int ord;
+        public String Tbl() {return tbl;} private final    String tbl;
+	public String Alias() {return "*";}
+}

140_dbs/src/gplx/dbs/Db_stmt.java

@@ -0,0 +1,65 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+import gplx.dbs.engines.*; import gplx.core.stores.*;
+public interface Db_stmt extends Rls_able {
+	Db_stmt Crt_bool_as_byte(String k, boolean v);
+	Db_stmt Val_bool_as_byte(String k, boolean v);
+	Db_stmt Val_bool_as_byte(boolean v);
+	Db_stmt Crt_byte(String k, byte v);
+	Db_stmt Val_byte(String k, byte v);
+	Db_stmt Val_byte(byte v);
+	Db_stmt Crt_int(String k, int v);
+	Db_stmt Val_int(String k, int v);
+	Db_stmt Val_int_by_bool(String k, boolean v);
+	Db_stmt Val_int(int v);
+	Db_stmt Crt_long(String k, long v);
+	Db_stmt Val_long(String k, long v);
+	Db_stmt Val_long(long v);
+	Db_stmt Crt_float(String k, float v);
+	Db_stmt Val_float(String k, float v);
+	Db_stmt Val_float(float v);
+	Db_stmt Crt_double(String k, double v);
+	Db_stmt Val_double(String k, double v);
+	Db_stmt Val_double(double v);
+	Db_stmt Crt_decimal(String k, Decimal_adp v);
+	Db_stmt Val_decimal(String k, Decimal_adp v);
+	Db_stmt Val_decimal(Decimal_adp v);
+	Db_stmt Crt_bry(String k, byte[] v);
+	Db_stmt Val_bry(String k, byte[] v);
+	Db_stmt Val_bry(byte[] v);
+	Db_stmt Crt_str(String k, String v);
+	Db_stmt Val_str(String k, String v);
+	Db_stmt Val_str(String v);
+	Db_stmt Crt_bry_as_str(String k, byte[] v);
+	Db_stmt Val_bry_as_str(String k, byte[] v);
+	Db_stmt Val_bry_as_str(byte[] v);
+	Db_stmt Val_rdr_(gplx.core.ios.streams.Io_stream_rdr rdr, long rdr_len);
+	Db_stmt Crt_date(String k, DateAdp v);
+	Db_stmt Val_date(String k, DateAdp v);
+	Db_stmt Crt_text(String k, String v);
+	Db_stmt Val_text(String k, String v);
+	boolean		Exec_insert();
+	int			Exec_update();
+	int			Exec_delete();
+	DataRdr		Exec_select();
+	Db_rdr		Exec_select__rls_auto();		// stmt is automatically released
+	Db_rdr		Exec_select__rls_manual();		// stmt must be released manually; for "batch" insert
+	Object		Exec_select_val();
+	void		Ctor_stmt(Db_engine engine, Db_qry qry);
+	Db_stmt		Clear();
+	Db_stmt		Reset_stmt();
+}

140_dbs/src/gplx/dbs/Db_stmt_.java

@@ -0,0 +1,74 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+import gplx.dbs.qrys.*;
+public class Db_stmt_ {
+	public static final    Db_stmt Null = new Db_stmt_sql();
+	public static Db_stmt new_insert_(Db_conn conn, String tbl, String... flds) {
+		Db_qry qry = Db_qry_insert.new_(tbl, flds);
+		return conn.Stmt_new(qry);
+	}
+	public static Db_stmt new_update_(Db_conn conn, String tbl, String[] where, String... flds) {
+		Db_qry qry = Db_qry_update.New(tbl, where, flds);
+		return conn.Stmt_new(qry);
+	}
+	public static Db_stmt new_delete_(Db_conn conn, String tbl, String... where) {
+		Db_qry_delete qry = Db_qry_.delete_(tbl, Db_crt_.eq_many_(where));
+		return conn.Stmt_new(qry);
+	}
+	public static Db_stmt new_select_(Db_conn conn, String tbl, String[] where, String... flds) {
+		Db_qry__select_cmd qry = Db_qry_.select_cols_(tbl, Db_crt_.eq_many_(where), flds);
+		return conn.Stmt_new(qry);
+	}
+	public static Db_stmt new_select_in_(Db_conn conn, String tbl, String in_fld, Object[] in_vals, String... flds) {
+		Db_qry__select_cmd qry = Db_qry_.select_cols_(tbl, Db_crt_.New_in(in_fld, in_vals), flds).Order_asc_(in_fld);
+		return conn.Stmt_new(qry);
+	}
+	public static Db_stmt new_select_all_(Db_conn conn, String tbl) {
+		return conn.Stmt_new(Db_qry_.select_tbl_(tbl));
+	}
+	public static Db_stmt new_select_as_rdr(Db_conn conn, Db_qry__select_in_tbl qry) {
+		return conn.Stmt_new(qry);
+	}
+	public static Db_stmt new_select_as_rdr(Db_conn conn, String sql) {
+		return conn.Stmt_new(Db_qry_sql.rdr_(sql));
+	}
+	public static Db_stmt New_sql_lines(Db_conn conn, String... lines) {
+		Db_qry qry = Db_qry_sql.sql_(String_.Concat_with_str("\n", lines));
+		return conn.Stmt_new(qry);
+	}
+	public static Err err_(Exception e, Db_stmt stmt, String proc) {
+		throw Err_.new_exc(e, "db", "db stmt failed", "proc", proc);
+	}
+	public static Err err_(Exception e, String tbl, String proc) {
+		throw Err_.new_exc(e, "core", "db call failed", "tbl", tbl, "proc", proc);
+	}
+	public static Db_stmt Rls(Db_stmt v) {if (v != null) v.Rls(); return null;}
+	public static void Val_by_obj(Db_stmt stmt, String key, Object val) {
+		int tid = Type_ids_.To_id_by_obj(val);
+		switch (tid) {
+			case Type_ids_.Id__bool:			stmt.Val_bool_as_byte	(key, Bool_.Cast(val)); break;
+			case Type_ids_.Id__byte:			stmt.Val_byte			(key, Byte_.Cast(val)); break;
+			case Type_ids_.Id__int:			stmt.Val_int			(key, Int_.Cast(val)); break;
+			case Type_ids_.Id__long:			stmt.Val_long			(key, Long_.cast(val)); break;
+			case Type_ids_.Id__float:			stmt.Val_float			(key, Float_.cast(val)); break;
+			case Type_ids_.Id__double:			stmt.Val_double			(key, Double_.cast(val)); break;
+			case Type_ids_.Id__str:			stmt.Val_str			(key, String_.cast(val)); break;
+			case Type_ids_.Id__bry:			stmt.Val_bry			(key, Bry_.cast(val)); break;
+			default:							throw Err_.new_unhandled_default(tid);
+		}
+	}
+}

140_dbs/src/gplx/dbs/Db_stmt_bldr.java

@@ -0,0 +1,46 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+public class Db_stmt_bldr {
+	private Db_conn conn; private Db_stmt create, update, delete;
+	private String tbl_name; private String[] flds_keys, flds_vals, flds_all;
+	public void Conn_(Db_conn v, String tbl_name, Dbmeta_fld_list flds, String... flds_keys) {
+		Conn_(v, tbl_name, flds.To_str_ary(), flds.To_str_ary_exclude(flds_keys), flds_keys);
+	}
+	public void Conn_(Db_conn v, String tbl_name, String[] flds_vals, String... flds_keys) {
+		Conn_(v, tbl_name, String_.Ary_add(flds_keys, flds_vals), flds_vals, flds_keys);
+	}
+	private void Conn_(Db_conn v, String tbl_name, String[] flds_all, String[] flds_vals, String... flds_keys) {
+		this.conn = v; this.tbl_name = tbl_name;
+		this.flds_all = flds_all; this.flds_vals = flds_vals; this.flds_keys = flds_keys;
+	}
+	public Db_stmt Get(byte cmd_mode) {
+		switch (cmd_mode) {
+			case Db_cmd_mode.Tid_create:	if (create == null) create = conn.Stmt_insert(tbl_name, flds_all);				return create;
+			case Db_cmd_mode.Tid_update:	if (update == null) update = conn.Stmt_update(tbl_name, flds_keys, flds_vals);	return update;
+			case Db_cmd_mode.Tid_delete:	if (delete == null) delete = conn.Stmt_delete(tbl_name, flds_keys);				return delete;
+			case Db_cmd_mode.Tid_ignore:	return Db_stmt_.Null;
+			default:						throw Err_.new_unhandled(cmd_mode);
+		}
+	}
+	public void Batch_bgn() {conn.Txn_bgn(tbl_name);}
+	public void Batch_end() {conn.Txn_end();}
+	public void Rls() {
+		create = Db_stmt_.Rls(create);
+		update = Db_stmt_.Rls(update);
+		delete = Db_stmt_.Rls(delete);
+	}
+}

140_dbs/src/gplx/dbs/Db_tbl.java

@@ -0,0 +1,20 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+public interface Db_tbl extends Rls_able {
+	String		Tbl_name();
+	void		Create_tbl();
+}

140_dbs/src/gplx/dbs/Db_tbl_.java

@@ -0,0 +1,28 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+public class Db_tbl_ {
+	public static void Create_tbl(Db_tbl... ary) {
+		int len = ary.length;
+		for (int i = 0; i < len; ++i)
+			ary[i].Create_tbl();
+	}
+	public static void Rls(Db_tbl... ary) {
+		int len = ary.length;
+		for (int i = 0; i < len; ++i)
+			ary[i].Rls();
+	}
+}

140_dbs/src/gplx/dbs/Db_tbl_owner.java

@@ -0,0 +1,19 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+public interface Db_tbl_owner {
+	Db_tbl Tbls__get_by_key(String key);
+}

140_dbs/src/gplx/dbs/Dbmeta_fld_itm.java

@@ -0,0 +1,79 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+import gplx.dbs.metas.*;
+public class Dbmeta_fld_itm {
+	public Dbmeta_fld_itm(String name, Dbmeta_fld_tid type) {
+		this.name = name; this.type = type;
+		this.primary = false; this.autonum = false; this.default_val = Default_value_null;
+	}
+	public String			Name()			{return name;} private final    String name;
+	public Dbmeta_fld_tid	Type()			{return type;} private final    Dbmeta_fld_tid type;
+	public int				Nullable_tid()	{return nullable_tid;} public Dbmeta_fld_itm Nullable_tid_(int v) {nullable_tid = v; return this;} private int nullable_tid;
+	public Dbmeta_fld_itm	Nullable_y_()	{return Nullable_tid_(Nullable_null);} 
+	public boolean				Primary()		{return primary;} public Dbmeta_fld_itm Primary_y_() {primary = true; return this;} private boolean primary; public Dbmeta_fld_itm Primary_n_() {primary = false; return this;}
+	public boolean				Autonum()		{return autonum;} public Dbmeta_fld_itm Autonum_y_() {autonum = true; return this;} private boolean autonum;
+	public Object			Default()		{return default_val;} public Dbmeta_fld_itm Default_(Object v) {default_val = v; return this;} private Object default_val;
+	public boolean Eq(Dbmeta_fld_itm comp) {
+		return	String_.Eq(name, comp.name)
+			&&	type.Eq(comp.type)
+			&&	nullable_tid == comp.nullable_tid
+			&&	primary == comp.primary
+			&&	autonum == comp.autonum
+			&& Object_.Eq(default_val, comp.default_val);
+	}
+
+	public static final int Nullable_unknown = 0, Nullable_null = 1, Nullable_not_null = 2;
+	public static final    Object Default_value_null = null;
+	public static final String Key_null = null;
+	public static final    String[] Str_ary_empty = String_.Ary_empty;
+	public static final    Dbmeta_fld_itm[] Ary_empty = new Dbmeta_fld_itm[0];
+
+	public static Dbmeta_fld_itm new_bool(String name)			{return new Dbmeta_fld_itm(name, Dbmeta_fld_tid.Itm__bool);}
+	public static Dbmeta_fld_itm new_byte(String name)			{return new Dbmeta_fld_itm(name, Dbmeta_fld_tid.Itm__byte);}
+	public static Dbmeta_fld_itm new_short(String name)			{return new Dbmeta_fld_itm(name, Dbmeta_fld_tid.Itm__short);}
+	public static Dbmeta_fld_itm new_int(String name)			{return new Dbmeta_fld_itm(name, Dbmeta_fld_tid.Itm__int);}
+	public static Dbmeta_fld_itm new_long(String name)			{return new Dbmeta_fld_itm(name, Dbmeta_fld_tid.Itm__long);}
+	public static Dbmeta_fld_itm new_float(String name)			{return new Dbmeta_fld_itm(name, Dbmeta_fld_tid.Itm__float);}
+	public static Dbmeta_fld_itm new_double(String name)		{return new Dbmeta_fld_itm(name, Dbmeta_fld_tid.Itm__double);}
+	public static Dbmeta_fld_itm new_text(String name)			{return new Dbmeta_fld_itm(name, Dbmeta_fld_tid.Itm__text);}
+	public static Dbmeta_fld_itm new_bry(String name)			{return new Dbmeta_fld_itm(name, Dbmeta_fld_tid.Itm__bry);}
+	public static Dbmeta_fld_itm new_str(String name, int len)	{return new Dbmeta_fld_itm(name, Dbmeta_fld_tid.Itm__str(len));}
+	public static String[] To_str_ary(Dbmeta_fld_itm[] ary) {
+		int len = ary.length;
+		String[] rv = new String[len];
+		for (int i = 0; i < len; ++i)
+			rv[i] = ary[i].name;
+		return rv;
+	}
+
+	public static String Make_or_null(Db_conn conn, Dbmeta_fld_list flds, String tbl_name, int fld_type, Object fld_dflt, String fld_name) {
+		boolean tbl_exists = conn.Meta_tbl_exists(tbl_name);
+		boolean fld_exists = true;
+		if (tbl_exists) {
+			fld_exists = conn.Meta_fld_exists(tbl_name, fld_name);
+			if (!fld_exists) return Dbmeta_fld_itm.Key_null;
+		}
+		Dbmeta_fld_itm fld = null;
+		switch (fld_type) {
+			case Dbmeta_fld_tid.Tid__int: fld = Dbmeta_fld_itm.new_int(fld_name); break;
+		}
+		if (fld_dflt != null) fld.Default_(fld_dflt);
+		flds.Add(fld);
+		return fld.name;
+	}
+	public static String To_double_str_by_int(int v) {return Int_.To_str(v) + ".0";}
+}

140_dbs/src/gplx/dbs/Dbmeta_fld_list.java

@@ -0,0 +1,106 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+public class Dbmeta_fld_list {
+	private final    Ordered_hash flds = Ordered_hash_.New();
+	public void Clear()									{flds.Clear(); str_ary = null; fld_ary = null;}
+	public int Len()									{return flds.Len();}
+	public boolean Has(String key)							{return flds.Has(key);}
+	public Dbmeta_fld_itm Get_by(String name)			{return (Dbmeta_fld_itm)flds.Get_by(name);}
+	public Dbmeta_fld_itm Get_at(int idx)				{return (Dbmeta_fld_itm)flds.Get_at(idx);}
+	public String Add_bool(String name)					{return Add(Dbmeta_fld_itm.new_bool(name));}
+	public String Add_byte(String name)					{return Add(Dbmeta_fld_itm.new_byte(name));}
+	public String Add_short(String name)				{return Add(Dbmeta_fld_itm.new_short(name));}
+	public String Add_int(String name)					{return Add(Dbmeta_fld_itm.new_int(name));}
+	public String Add_int_pkey(String name)				{return Add(Dbmeta_fld_itm.new_int(name).Primary_y_());}
+	public String Add_int_pkey_autonum(String name)		{return Add(Dbmeta_fld_itm.new_int(name).Primary_y_().Autonum_y_());}
+	public String Add_int_autonum(String name)			{return Add(Dbmeta_fld_itm.new_int(name).Autonum_y_());}
+	public String Add_int_dflt(String name, int dflt)	{return Add(Dbmeta_fld_itm.new_int(name).Default_(dflt));}
+	public String Add_long(String name)					{return Add(Dbmeta_fld_itm.new_long(name));}
+	public String Add_float(String name)				{return Add(Dbmeta_fld_itm.new_float(name));}
+	public String Add_double(String name)				{return Add(Dbmeta_fld_itm.new_double(name));}
+	public String Add_text(String name)					{return Add(Dbmeta_fld_itm.new_text(name));}
+	public String Add_bry(String name)					{return Add(Dbmeta_fld_itm.new_bry(name));}
+	public String Add_str(String name, int len)			{return Add(Dbmeta_fld_itm.new_str(name, len));}
+	public String Add_date(String name)					{return Add(Dbmeta_fld_itm.new_str(name, 32));}
+	public String Add_str_pkey(String name, int len)	{return Add(Dbmeta_fld_itm.new_str(name, len).Primary_y_());}
+	public String Add_str_null(String name, int len)	{return Add(Dbmeta_fld_itm.new_str(name, len).Nullable_y_());}
+	public String Add_str_dflt(String name, int len, String dflt)
+														{return Add(Dbmeta_fld_itm.new_str(name, len).Default_(dflt));}
+	public String Add(Dbmeta_fld_itm fld) {
+		fld_ary = null; str_ary = null;
+		String name = fld.Name();
+		flds.Add(name, fld);
+		return name;
+	}
+	public void Del(String key) {
+		fld_ary = null; str_ary = null;
+		flds.Del(key);
+	}
+	public void Insert(int pos, Dbmeta_fld_itm fld) {
+		fld_ary = null; str_ary = null;
+		flds.Add_at(pos, fld);
+	}
+
+	public Dbmeta_fld_list New_int(String name)			{Add(Dbmeta_fld_itm.new_int(name)); return this;}
+	public Dbmeta_fld_list New_fld(Dbmeta_fld_itm fld)	{Add(fld); return this;}
+	public Dbmeta_fld_list Clone() {
+		Dbmeta_fld_list rv = new Dbmeta_fld_list();
+		int len = this.Len();
+		for (int i = 0; i < len; ++i)
+			rv.Add(this.Get_at(i));
+		return rv;
+	}
+	public Dbmeta_fld_itm[] To_fld_ary()		{if (fld_ary == null) fld_ary = (Dbmeta_fld_itm[])flds.To_ary(Dbmeta_fld_itm.class); return fld_ary;} private Dbmeta_fld_itm[] fld_ary;
+	public String[] To_str_ary() {
+		if (str_ary == null) {
+			int len = flds.Len();
+			this.str_ary = new String[len];
+			for (int i = 0; i < len; ++i) {
+				Dbmeta_fld_itm fld = (Dbmeta_fld_itm)flds.Get_at(i);
+				str_ary[i] = fld.Name();
+			}
+		}
+		return str_ary;
+	}	private String[] str_ary;
+	public String[] To_str_ary_wo_autonum()	{
+		int len = flds.Count();
+		List_adp rv = List_adp_.New();
+		for (int i = 0; i < len; ++i) {
+			Dbmeta_fld_itm fld = (Dbmeta_fld_itm)flds.Get_at(i);
+			if (fld.Autonum()) continue;
+			rv.Add(fld.Name());
+		}
+		return (String[])rv.To_ary(String.class);
+	} 
+	public String[] To_str_ary_exclude(String[] ary) {
+		Hash_adp ary_hash = Hash_adp_.New();
+		List_adp rv = List_adp_.New();
+		int ary_len = ary.length;
+		for (int i = 0; i < ary_len; ++i) {
+			String ary_itm = ary[i];
+			ary_hash.Add(ary_itm, ary_itm);
+		}
+		int fld_len = flds.Count();
+		for (int i = 0; i < fld_len; ++i) {
+			Dbmeta_fld_itm fld = (Dbmeta_fld_itm)flds.Get_at(i);
+			String fld_key = fld.Name();
+			if (ary_hash.Has(fld_key)) continue;
+			rv.Add(fld_key);
+		}
+		return rv.To_str_ary();
+	}
+}

140_dbs/src/gplx/dbs/Dbmeta_fld_tid.java

@@ -0,0 +1,71 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+import gplx.dbs.engines.sqlite.*;	// for Tid_sqlite; note that Tid_sqlite is not used, and only exists for doc purposes
+public class Dbmeta_fld_tid {
+	public Dbmeta_fld_tid(int tid_ansi, int tid_sqlite, byte[] name, int len_1, int len_2) {
+		this.tid_ansi = tid_ansi; this.tid_sqlite = tid_sqlite; this.name = name; this.len_1 = len_1; this.len_2 = len_2;
+	}
+	public int Tid_ansi()	{return tid_ansi;} private final    int tid_ansi;
+	public int Tid_sqlite() {return tid_sqlite;} private final    int tid_sqlite;
+	public byte[] Name()	{return name;} private final    byte[] name;
+	public int Len_1()		{return len_1;} private final    int len_1;
+	public int Len_2()		{return len_2;} private final    int len_2;
+	public boolean Eq(Dbmeta_fld_tid comp) {
+		return	tid_ansi == comp.tid_ansi
+			&&	tid_sqlite == comp.tid_sqlite
+			&&	Bry_.Eq(name, comp.name)
+			&&	len_1 == comp.len_1
+			&&	len_2 == comp.len_2;
+	}
+
+	public static final int Tid__bool = 0, Tid__byte = 1, Tid__short = 2, Tid__int = 3, Tid__long = 4, Tid__float = 5, Tid__double = 6, Tid__str = 7, Tid__text = 8, Tid__bry = 9, Tid__decimal = 10, Tid__date = 11;
+	public static final    Dbmeta_fld_tid 
+	  Itm__byte			= new Dbmeta_fld_tid(Dbmeta_fld_tid.Tid__byte		, Sqlite_tid.Tid_int		, Bry_.new_a7("tinyint")	, -1, -1)
+	, Itm__short		= new Dbmeta_fld_tid(Dbmeta_fld_tid.Tid__short		, Sqlite_tid.Tid_int		, Bry_.new_a7("smallint")	, -1, -1)
+	, Itm__int			= new Dbmeta_fld_tid(Dbmeta_fld_tid.Tid__int		, Sqlite_tid.Tid_int		, Bry_.new_a7("integer")	, -1, -1)
+	, Itm__long			= new Dbmeta_fld_tid(Dbmeta_fld_tid.Tid__long		, Sqlite_tid.Tid_int		, Bry_.new_a7("bigint")		, -1, -1)
+	, Itm__text			= new Dbmeta_fld_tid(Dbmeta_fld_tid.Tid__text		, Sqlite_tid.Tid_text		, Bry_.new_a7("text")		, -1, -1)
+	, Itm__bry			= new Dbmeta_fld_tid(Dbmeta_fld_tid.Tid__bry		, Sqlite_tid.Tid_none		, Bry_.new_a7("blob")		, -1, -1)
+	, Itm__float		= new Dbmeta_fld_tid(Dbmeta_fld_tid.Tid__float		, Sqlite_tid.Tid_real		, Bry_.new_a7("float")		, -1, -1)
+	, Itm__double		= new Dbmeta_fld_tid(Dbmeta_fld_tid.Tid__double		, Sqlite_tid.Tid_real		, Bry_.new_a7("double")		, -1, -1)
+	, Itm__numeric		= new Dbmeta_fld_tid(Dbmeta_fld_tid.Tid__decimal	, Sqlite_tid.Tid_numeric	, Bry_.new_a7("numeric")	, -1, -1)
+	, Itm__bool			= new Dbmeta_fld_tid(Dbmeta_fld_tid.Tid__bool		, Sqlite_tid.Tid_numeric	, Bry_.new_a7("bit")		, -1, -1)	// "bit" is not SQLITE
+	, Itm__date			= new Dbmeta_fld_tid(Dbmeta_fld_tid.Tid__date		, Sqlite_tid.Tid_numeric	, Bry_.new_a7("date")		, -1, -1)
+	;
+	public static Dbmeta_fld_tid Itm__str		(int len)				{return new Dbmeta_fld_tid(Dbmeta_fld_tid.Tid__str		, Sqlite_tid.Tid_text		, Bry_.new_a7("varchar")	, len, -1);}
+	public static Dbmeta_fld_tid Itm__decimal	(int len_1, int len_2)	{return new Dbmeta_fld_tid(Dbmeta_fld_tid.Tid__decimal	, Sqlite_tid.Tid_numeric	, Bry_.new_a7("decimal")	, len_1, len_2);}
+	public static Dbmeta_fld_tid New(int tid, int len1) {
+		switch (tid) {
+			case Dbmeta_fld_tid.Tid__bool:		return Itm__bool;
+			case Dbmeta_fld_tid.Tid__byte:		return Itm__byte;
+			case Dbmeta_fld_tid.Tid__short:		return Itm__short;
+			case Dbmeta_fld_tid.Tid__int:		return Itm__int;
+			case Dbmeta_fld_tid.Tid__long:		return Itm__long;
+			case Dbmeta_fld_tid.Tid__float:		return Itm__float;
+			case Dbmeta_fld_tid.Tid__double:	return Itm__double;
+			case Dbmeta_fld_tid.Tid__str:		return Itm__str(len1);
+			case Dbmeta_fld_tid.Tid__text:		return Itm__text;
+			case Dbmeta_fld_tid.Tid__bry:		return Itm__bry;
+			case Dbmeta_fld_tid.Tid__date:		return Itm__date;
+			case Dbmeta_fld_tid.Tid__decimal:	//	return Itm__decimal(len1);
+			default:							throw Err_.new_unhandled(tid);
+		}
+	}
+	public static Dbmeta_fld_itm To_itm(String raw) {
+		return null;
+	}
+}

140_dbs/src/gplx/dbs/Dbmeta_idx_itm.java

@@ -0,0 +1,52 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+import gplx.dbs.metas.*; import gplx.dbs.sqls.*; import gplx.dbs.sqls.wtrs.*;
+public class Dbmeta_idx_itm {
+	public Dbmeta_idx_itm(boolean unique, String tbl, String name, Dbmeta_idx_fld[] flds) {
+		this.tbl = tbl; this.name = name; this.unique = unique; this.Flds = flds;
+	}
+	public String Tbl() {return tbl;} private final    String tbl;
+	public String Name() {return name;} private final    String name;		
+	public boolean Unique() {return unique;} private final    boolean unique;
+	public final    Dbmeta_idx_fld[] Flds;
+	public String To_sql_create(Sql_qry_wtr sql_wtr) {return sql_wtr.Schema_wtr().Bld_create_idx(this);}
+	public boolean Eq(Dbmeta_idx_itm comp) {
+		return String_.Eq(name, comp.name)
+			&& unique == comp.unique
+			&& tbl == comp.tbl
+			&& Dbmeta_idx_fld.Ary_eq(Flds, comp.Flds);
+	}
+	public static Dbmeta_idx_itm new_unique_by_name			(String tbl, String name, String... flds)			{return new Dbmeta_idx_itm(Bool_.Y, tbl, name, To_fld_ary(flds));}
+	public static Dbmeta_idx_itm new_normal_by_name			(String tbl, String name, Dbmeta_idx_fld... flds)	{return new Dbmeta_idx_itm(Bool_.N, tbl, name, flds);}
+	public static Dbmeta_idx_itm new_normal_by_name			(String tbl, String name, String... flds)	{return new Dbmeta_idx_itm(Bool_.N, tbl, name, To_fld_ary(flds));}
+	public static Dbmeta_idx_itm new_unique_by_tbl			(String tbl, String name, String... flds)	{return new Dbmeta_idx_itm(Bool_.Y, tbl, Bld_idx_name(tbl, name), To_fld_ary(flds));}
+	public static Dbmeta_idx_itm new_normal_by_tbl			(String tbl, String name, Dbmeta_idx_fld... flds)	{return new Dbmeta_idx_itm(Bool_.N, tbl, Bld_idx_name(tbl, name), flds);}
+	public static Dbmeta_idx_itm new_normal_by_tbl			(String tbl, String name, String... flds)	{return new Dbmeta_idx_itm(Bool_.N, tbl, Bld_idx_name(tbl, name), To_fld_ary(flds));}
+	public static Dbmeta_idx_itm new_unique_by_tbl_wo_null	(String tbl, String name, String... flds)	{return new Dbmeta_idx_itm(Bool_.Y, tbl, Bld_idx_name(tbl, name), To_fld_ary(flds));}
+	public static Dbmeta_idx_itm new_normal_by_tbl_wo_null	(String tbl, String name, String... flds)	{return new Dbmeta_idx_itm(Bool_.N, tbl, Bld_idx_name(tbl, name), To_fld_ary(flds));}
+	public static String Bld_idx_name(String tbl, String suffix) {return String_.Concat(tbl, "__", suffix);}
+	public static final    Dbmeta_idx_itm[] Ary_empty = new Dbmeta_idx_itm[0];
+	public static Dbmeta_idx_fld[] To_fld_ary(String[] ary) {
+		int len = ary.length;
+		Dbmeta_idx_fld[] rv = new Dbmeta_idx_fld[len];
+		for (int i = 0; i < len; ++i) {
+			String itm = ary[i]; if (itm == null) continue;
+			rv[i] = new Dbmeta_idx_fld(itm, Dbmeta_idx_fld.Sort_tid__none);
+		}
+		return rv;
+	}
+}

140_dbs/src/gplx/dbs/Dbmeta_tbl_itm.java

@@ -0,0 +1,41 @@
+/*
+XOWA: the XOWA Offline Wiki Application
+Copyright (C) 2012-2017 gnosygnu@gmail.com
+
+XOWA is licensed under the terms of the General Public License (GPL) Version 3,
+or alternatively under the terms of the Apache License Version 2.0.
+
+You may use XOWA according to either of these licenses as is most appropriate
+for your project on a case-by-case basis.
+
+The terms of each license can be found in the source code repository:
+
+GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
+Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
+*/
+package gplx.dbs; import gplx.*;
+import gplx.dbs.metas.*; import gplx.dbs.sqls.*; import gplx.dbs.sqls.wtrs.*;
+public class Dbmeta_tbl_itm {
+	public String Name() {return name;} private String name;
+	public Dbmeta_idx_mgr Idxs() {return idxs;} private final Dbmeta_idx_mgr idxs = new Dbmeta_idx_mgr();
+	public Dbmeta_fld_mgr Flds() {return flds;} private final Dbmeta_fld_mgr flds = new Dbmeta_fld_mgr();
+	public String To_sql_create(Sql_qry_wtr sql_wtr) {return sql_wtr.Schema_wtr().Bld_create_tbl(this);}
+
+	public static Dbmeta_tbl_itm New(String name, Dbmeta_fld_list flds, Dbmeta_idx_itm... idxs)	{return New(name, flds.To_fld_ary(), idxs);}
+	public static Dbmeta_tbl_itm New(String name, Dbmeta_fld_itm... flds)							{return New(name, flds, Dbmeta_idx_itm.Ary_empty);}
+	public static Dbmeta_tbl_itm New(String name, Dbmeta_fld_itm[] flds, Dbmeta_idx_itm... idxs) {
+		Dbmeta_tbl_itm rv = new Dbmeta_tbl_itm();
+		rv.name = name;
+		if (flds != null) {
+			int flds_len = flds.length;
+			for (int i = 0; i < flds_len; ++i)
+				rv.flds.Add(flds[i]);
+		}
+		if (idxs != null) {
+			int idxs_len = idxs.length;
+			for (int i = 0; i < idxs_len; ++i)
+				rv.idxs.Add(idxs[i]);
+		}
+		return rv;
+	}
+}

140_dbs/src/gplx/dbs/conn_props/Db_conn_props_mgr.java

@@ -13,3 +13,14 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.conn_props; import gplx.*; import gplx.dbs.*;
+public class Db_conn_props_mgr {
+	private final    Ordered_hash hash = Ordered_hash_.New();
+	public boolean Has(String key) {return hash.Has(key);}
+	public boolean Match(String key, String expd_val) {
+		String actl_val = (String)hash.Get_by(key);
+		return actl_val == null ? false : String_.Eq(expd_val,actl_val);
+	}
+	public void Add(String key, String val) {hash.Add(key, val);}
+	public void Del(String key)				{hash.Del(key);}
+}

140_dbs/src/gplx/dbs/diffs/Gdif_core.java

@@ -13,3 +13,32 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.diffs; import gplx.*; import gplx.dbs.*;
+import gplx.dbs.diffs.itms.*;
+import gplx.dbs.diffs.builds.*;
+public class Gdif_core {
+	private final    Db_conn conn;
+	private final    Gdif_job_tbl job_tbl;
+	private final    Gdif_cmd_tbl cmd_tbl;
+	private final    Gdif_txn_tbl txn_tbl;
+	public Gdif_core(Db_conn conn) {
+		this.conn = conn;
+		this.db = new Gdif_db(conn);
+		this.job_tbl = db.Job_tbl();
+		this.cmd_tbl = db.Cmd_tbl();
+		this.txn_tbl = db.Txn_tbl();
+	}
+	public Gdif_db Db() {return db;} private final    Gdif_db db;
+	public Gdif_job_itm New_job(String name, String made_by) {
+		int job_id = conn.Sys_mgr().Autonum_next(job_tbl.Tbl_name(), job_tbl.Fld_job_id());
+		return job_tbl.Insert(job_id, name, made_by, Datetime_now.Get().XtoUtc(), "");
+	}
+	public Gdif_cmd_itm New_cmd(Gdif_bldr_ctx ctx, int tid) {
+		ctx.Cur_cmd_count++;
+		return cmd_tbl.Insert(ctx.Cur_job.Id, ctx.Cur_cmd_count, tid, "");
+	}
+	public Gdif_txn_itm New_txn(Gdif_bldr_ctx ctx, int cmd_id, int owner_txn) {
+		ctx.Cur_txn_count++;
+		return txn_tbl.Insert(ctx.Cur_job.Id, ctx.Cur_txn_count, cmd_id, owner_txn);
+	}
+}

140_dbs/src/gplx/dbs/diffs/Gdif_db.java

@@ -13,3 +13,17 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.diffs; import gplx.*; import gplx.dbs.*;
+import gplx.dbs.diffs.itms.*;
+public class Gdif_db {
+	public Gdif_db(Db_conn conn) {
+		this.conn = conn;
+		this.job_tbl = new Gdif_job_tbl(conn);
+		this.cmd_tbl = new Gdif_cmd_tbl(conn);
+		this.txn_tbl = new Gdif_txn_tbl(conn);
+	}
+	public Db_conn Conn() {return conn;} private final Db_conn conn;
+	public Gdif_job_tbl Job_tbl() {return job_tbl;} private final Gdif_job_tbl job_tbl;
+	public Gdif_cmd_tbl Cmd_tbl() {return cmd_tbl;} private final Gdif_cmd_tbl cmd_tbl;
+	public Gdif_txn_tbl Txn_tbl() {return txn_tbl;} private final Gdif_txn_tbl txn_tbl;
+}

140_dbs/src/gplx/dbs/diffs/Gdif_db_.java

@@ -13,3 +13,19 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.diffs; import gplx.*; import gplx.dbs.*;
+public class Gdif_db_ {
+	public static final String
+	  Fld__dif_txn			= "dif_txn"		// 0+ where 0+ is defined in a tbl
+	, Fld__dif_uid			= "dif_uid"		// 0+
+	, Fld__dif_type			= "dif_type"	// I,U,D,M
+	, Fld__dif_db_trg		= "dif_db_trg"	// -1 for single-db tables; 0+ for multiple-db tables
+	, Fld__dif_db_src		= "dif_db_src"	// -1 for I,U,D; 0+ for M
+	;
+	public static final byte
+	  Tid__insert = 0
+	, Tid__update = 1
+	, Tid__delete = 2
+	, Tid__move   = 3
+	;
+}

140_dbs/src/gplx/dbs/diffs/Gfdb_diff_cmd.java

@@ -13,3 +13,44 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.diffs; import gplx.*; import gplx.dbs.*;
+import gplx.dbs.metas.*; import gplx.dbs.diffs.builds.*;
+class Gfdb_diff_cmd {
+	private final Gfdb_diff_wkr__db diff_bldr_wkr = new Gfdb_diff_wkr__db();
+	private final Gfdb_diff_bldr diff_bldr = new Gfdb_diff_bldr();
+	public Gfdb_diff_cmd() {
+		diff_bldr.Init(diff_bldr_wkr);
+	}
+	public Gfdb_diff_job New_job(Gdif_db db, String guid, String name, String made_by, String desc) {
+		return new Gfdb_diff_job(db);
+	}
+	public void Bld(Gfdb_diff_job job, Gfdb_diff_tbl_mgr lhs_mgr, Gfdb_diff_tbl_mgr rhs_mgr) {
+		diff_bldr_wkr.Init_conn(job.Db(), 1000);			
+		int rhs_len = rhs_mgr.Len();
+		for (int i = 0; i < rhs_len; ++i) {
+			Gfdb_diff_tbl rhs_tbl = rhs_mgr.Get_at(i);
+			Gfdb_diff_tbl lhs_tbl = lhs_mgr.Get_by(rhs_tbl.Name);
+			if (lhs_tbl == null) {
+				// Add_cmd_tbl_create();
+				// Add_cmd_tbl_insert_all());
+			}
+			else {
+				// Compare_flds();
+				// Compare_idxs();
+				// diff_bldr.Compare(lhs_tbl, rhs_tbl);
+			}
+		}
+		int lhs_len = lhs_mgr.Len();
+		for (int i = 0; i < lhs_len; ++i) {
+			Gfdb_diff_tbl lhs_tbl = lhs_mgr.Get_at(i);
+			if (lhs_tbl == null) {
+				// Add_cmd_dat_delete_all());
+				// Add_cmd_tbl_delete();
+			}
+		}			
+	}
+}
+class Gfdb_diff_job {
+	public Gfdb_diff_job(Gdif_db db) {this.db = db;}
+	public Gdif_db Db() {return db;} private Gdif_db db;
+}

140_dbs/src/gplx/dbs/diffs/Gfdb_diff_tbl.java

@@ -13,3 +13,72 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.diffs; import gplx.*; import gplx.dbs.*;
+import gplx.dbs.metas.*;
+public class Gfdb_diff_tbl {		
+	public Gfdb_diff_tbl(String name, Dbmeta_fld_itm[] flds, Dbmeta_fld_itm[] keys, Dbmeta_fld_itm[] vals) {
+		this.Name = name; this.Flds = flds; this.Keys = keys; this.Vals = vals;
+	}
+	public final String Name;
+	public final Dbmeta_fld_itm[] Flds;
+	public final Dbmeta_fld_itm[] Keys;
+	public final Dbmeta_fld_itm[] Vals;
+	public Db_rdr Make_rdr(Db_conn conn) {
+		Db_stmt stmt = conn.Stmt_select_order(Name, Dbmeta_fld_itm.To_str_ary(Flds), Dbmeta_fld_itm.Str_ary_empty, Dbmeta_fld_itm.To_str_ary(Keys));
+		return stmt.Exec_select__rls_auto();
+	}
+
+	public static Gfdb_diff_tbl New(Dbmeta_tbl_itm tbl) {
+		Dbmeta_fld_mgr flds = tbl.Flds();
+		Dbmeta_fld_mgr keys = Calc_keys(tbl);
+		Dbmeta_fld_mgr vals = Calc_vals(tbl.Flds(), keys);
+		return new Gfdb_diff_tbl(tbl.Name(), flds.To_ary(), keys.To_ary(), vals.To_ary());
+	}
+	public static Dbmeta_fld_mgr Calc_keys(Dbmeta_tbl_itm tbl) {
+		Dbmeta_fld_mgr rv = new Dbmeta_fld_mgr();
+		// try to find primary
+		Dbmeta_fld_mgr flds = tbl.Flds();
+		int flds_len = flds.Len();
+		for (int i = 0; i < flds_len; ++i) {
+			Dbmeta_fld_itm fld = flds.Get_at(i);
+			if (fld.Primary()) {
+				rv.Add(fld);
+				return rv;
+			}
+		}
+		// try to find shortest unique index
+		Dbmeta_idx_itm unique_idx = null; int unique_idx_len = Int_.Max_value;
+		Dbmeta_idx_mgr idxs = tbl.Idxs();
+		int idxs_len = idxs.Len();
+		for (int i = 0; i < idxs_len; ++i) {
+			Dbmeta_idx_itm idx = idxs.Get_at(i);
+			if (idx.Unique() && idx.Flds.length < unique_idx_len) {	// get first shortest unique index; note that "<" is "get first" whereas "<=" is "get last"
+				unique_idx = idx;
+				unique_idx_len = idx.Flds.length;
+				break;
+			}
+		}
+		if (unique_idx != null) {
+			Dbmeta_idx_fld[] idx_flds = unique_idx.Flds;
+			int idx_flds_len = idx_flds.length;
+			for (int i = 0; i < idx_flds_len; ++i)
+				rv.Add(flds.Get_by(idx_flds[i].Name));
+			return rv;
+		}
+		// just add all
+		for (int i = 0; i < flds_len; ++i) {
+			Dbmeta_fld_itm fld = flds.Get_at(i);
+			rv.Add(fld);					
+		}
+		return rv;
+	}
+	private static Dbmeta_fld_mgr Calc_vals(Dbmeta_fld_mgr flds, Dbmeta_fld_mgr keys) {
+		Dbmeta_fld_mgr rv = new Dbmeta_fld_mgr();
+		int flds_len = flds.Len();
+		for (int i = 0; i < flds_len; ++i) {
+			Dbmeta_fld_itm fld = flds.Get_at(i);
+			if (!keys.Has(fld.Name())) rv.Add(fld);
+		}
+		return rv;
+	}
+}

140_dbs/src/gplx/dbs/diffs/Gfdb_diff_tbl_mgr.java

@@ -13,3 +13,21 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.diffs; import gplx.*; import gplx.dbs.*;
+class Gfdb_diff_tbl_mgr {
+	private final Ordered_hash hash = Ordered_hash_.New();
+	public int Len() {return hash.Count();}
+	public Gfdb_diff_tbl Get_at(int idx) {return (Gfdb_diff_tbl)hash.Get_at(idx);}
+	public Gfdb_diff_tbl Get_by(String key) {return (Gfdb_diff_tbl)hash.Get_by(key);}
+}
+class Gfdb_diff_tbl_mgr__sqlite {
+	public void Fill(Gfdb_diff_tbl_mgr tbl_mgr, Db_conn conn) {
+		// String schema_str = ""; // conn.Get_schema();
+	}
+	public void Fill(Gfdb_diff_tbl_mgr tbl_mgr, String schema_str) {
+		/*
+		Db_conn conn = null;
+		conn.Meta_get_tbls(Gfdb_diff_tbl_mgr tbl_mgr, "");
+		*/
+	}
+}	

140_dbs/src/gplx/dbs/diffs/Gfdb_rdr_utl_.java

@@ -13,3 +13,64 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.diffs; import gplx.*; import gplx.dbs.*;
+import gplx.dbs.metas.*;
+public class Gfdb_rdr_utl_ {
+	public static int Compare(Dbmeta_fld_itm[] flds, int len, Db_rdr lhs_rdr, Db_rdr rhs_rdr) {
+		int comp = CompareAble_.Same;
+		for (int i = 0; i < len; ++i) {
+			Dbmeta_fld_itm fld = flds[i];
+			String fld_name = fld.Name();
+			int tid = fld.Type().Tid_ansi();
+			switch (tid) {
+				case Dbmeta_fld_tid.Tid__bool:		comp = Bool_.Compare	(lhs_rdr.Read_bool_by_byte(fld_name), rhs_rdr.Read_bool_by_byte(fld_name)); break;
+				case Dbmeta_fld_tid.Tid__byte:		comp = Byte_.Compare	(lhs_rdr.Read_byte(fld_name)		, rhs_rdr.Read_byte(fld_name)); break;
+				case Dbmeta_fld_tid.Tid__int:		comp = Int_.Compare		(lhs_rdr.Read_int(fld_name)			, rhs_rdr.Read_int(fld_name)); break;
+				case Dbmeta_fld_tid.Tid__long:		comp = Long_.Compare	(lhs_rdr.Read_long(fld_name)		, rhs_rdr.Read_long(fld_name)); break;
+				case Dbmeta_fld_tid.Tid__float:		comp = Float_.Compare	(lhs_rdr.Read_float(fld_name)		, rhs_rdr.Read_float(fld_name)); break;
+				case Dbmeta_fld_tid.Tid__double:	comp = Double_.Compare	(lhs_rdr.Read_double(fld_name)		, rhs_rdr.Read_double(fld_name)); break;
+				case Dbmeta_fld_tid.Tid__str:		comp = String_.Compare	(lhs_rdr.Read_str(fld_name)			, rhs_rdr.Read_str(fld_name)); break;
+				case Dbmeta_fld_tid.Tid__bry:		comp = Bry_.Compare		(lhs_rdr.Read_bry(fld_name)			, rhs_rdr.Read_bry(fld_name)); break;
+				default:							throw Err_.new_unhandled(tid);
+			}
+			if (comp != CompareAble_.Same) return comp;
+		}
+		return CompareAble_.Same;
+	}
+	public static void Stmt_args(Db_stmt stmt, Dbmeta_fld_itm[] flds, int bgn, int end, Db_rdr rdr) {
+		for (int i = bgn; i < end; ++i) {
+			Dbmeta_fld_itm fld = flds[i];
+			String fld_name = fld.Name();
+			int tid = fld.Type().Tid_ansi();
+			switch (tid) {
+				case Dbmeta_fld_tid.Tid__bool:		stmt.Val_bool_as_byte	(fld_name, rdr.Read_bool_by_byte(fld_name)); break;
+				case Dbmeta_fld_tid.Tid__byte:		stmt.Val_byte			(fld_name, rdr.Read_byte(fld_name)); break;
+				case Dbmeta_fld_tid.Tid__int:		stmt.Val_int			(fld_name, rdr.Read_int(fld_name)); break;
+				case Dbmeta_fld_tid.Tid__long:		stmt.Val_long			(fld_name, rdr.Read_long(fld_name)); break;
+				case Dbmeta_fld_tid.Tid__float:		stmt.Val_float			(fld_name, rdr.Read_float(fld_name)); break;
+				case Dbmeta_fld_tid.Tid__double:	stmt.Val_double			(fld_name, rdr.Read_double(fld_name)); break;
+				case Dbmeta_fld_tid.Tid__str:		stmt.Val_str			(fld_name, rdr.Read_str(fld_name)); break;
+				case Dbmeta_fld_tid.Tid__bry:		stmt.Val_bry			(fld_name, rdr.Read_bry(fld_name)); break;
+				default:							throw Err_.new_unhandled(tid);
+			}
+		}
+	}
+	public static void Stmt_args(Db_stmt stmt, Dbmeta_fld_list flds, int bgn, int end, Db_rdr rdr) {
+		for (int i = bgn; i < end; ++i) {
+			Dbmeta_fld_itm fld = flds.Get_at(i);
+			String fld_name = fld.Name();
+			int tid = fld.Type().Tid_ansi();
+			switch (tid) {
+				case Dbmeta_fld_tid.Tid__bool:		stmt.Val_bool_as_byte	(fld_name, rdr.Read_bool_by_byte(fld_name)); break;
+				case Dbmeta_fld_tid.Tid__byte:		stmt.Val_byte			(fld_name, rdr.Read_byte(fld_name)); break;
+				case Dbmeta_fld_tid.Tid__int:		stmt.Val_int			(fld_name, rdr.Read_int(fld_name)); break;
+				case Dbmeta_fld_tid.Tid__long:		stmt.Val_long			(fld_name, rdr.Read_long(fld_name)); break;
+				case Dbmeta_fld_tid.Tid__float:		stmt.Val_float			(fld_name, rdr.Read_float(fld_name)); break;
+				case Dbmeta_fld_tid.Tid__double:	stmt.Val_double			(fld_name, rdr.Read_double(fld_name)); break;
+				case Dbmeta_fld_tid.Tid__str:		stmt.Val_str			(fld_name, rdr.Read_str(fld_name)); break;
+				case Dbmeta_fld_tid.Tid__bry:		stmt.Val_bry			(fld_name, rdr.Read_bry(fld_name)); break;
+				default:							throw Err_.new_unhandled(tid);
+			}
+		}
+	}
+}

140_dbs/src/gplx/dbs/diffs/builds/Gdif_bldr_ctx.java

@@ -13,3 +13,24 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.diffs.builds; import gplx.*; import gplx.dbs.*; import gplx.dbs.diffs.*;
+import gplx.dbs.diffs.itms.*;
+public class Gdif_bldr_ctx {
+	public Gdif_bldr_ctx() {}
+	public Gdif_core Core;
+	public Gdif_job_itm Cur_job;
+	public Gdif_cmd_itm Cur_cmd;
+	public Gdif_txn_itm Cur_txn;
+	public int Cur_cmd_count;
+	public int Cur_txn_count;
+	public Gdif_bldr_ctx Init(Gdif_core core, Gdif_job_itm cur_job) {
+		this.Core = core; this.Cur_job = cur_job;
+		return this;
+	}
+	public void Clear() {
+		Cur_cmd_count = 0; Cur_txn_count = 0;
+		Cur_job = null;
+		Cur_cmd = null;
+		Cur_txn = null;
+	}
+}

140_dbs/src/gplx/dbs/diffs/builds/Gfdb_diff_bldr.java

@@ -13,3 +13,26 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.diffs.builds; import gplx.*; import gplx.dbs.*; import gplx.dbs.diffs.*;
+import gplx.dbs.*;
+public class Gfdb_diff_bldr {
+	private Gfdb_diff_rdr_comparer rdr_comparer = new Gfdb_diff_rdr_comparer();
+	private Gfdb_diff_wkr diff_wkr;
+	public void Init(Gfdb_diff_wkr diff_wkr) {this.diff_wkr = diff_wkr;}
+	public void Compare(Gdif_bldr_ctx ctx, Gfdb_diff_tbl tbl, Db_conn old_conn, Db_conn new_conn) {
+		Db_rdr old_rdr = tbl.Make_rdr(old_conn), new_rdr = tbl.Make_rdr(new_conn);
+		rdr_comparer.Init_rdrs(tbl, old_rdr, new_rdr);
+		diff_wkr.Init_rdrs(ctx, tbl, old_rdr, new_rdr);
+		boolean loop = true;
+		while (loop) {
+			int rslt = rdr_comparer.Compare();
+			switch (rslt) {
+				case Gfdb_diff_rdr_comparer.Rslt__same:				diff_wkr.Handle_same(); break;
+				case Gfdb_diff_rdr_comparer.Rslt__old_missing:		diff_wkr.Handle_old_missing(); break;
+				case Gfdb_diff_rdr_comparer.Rslt__new_missing:		diff_wkr.Handle_new_missing(); break;
+				case Gfdb_diff_rdr_comparer.Rslt__done:				loop = false; break;
+			}
+		}
+		diff_wkr.Term_tbls();
+	}
+}

140_dbs/src/gplx/dbs/diffs/builds/Gfdb_diff_bldr_tst.java

@@ -13,3 +13,93 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.diffs.builds; import gplx.*; import gplx.dbs.*; import gplx.dbs.diffs.*;
+import org.junit.*;
+import gplx.dbs.*; import gplx.dbs.metas.*; import gplx.dbs.engines.mems.*;
+public class Gfdb_diff_bldr_tst {
+	private final    Gfdb_diff_bldr_fxt fxt = new Gfdb_diff_bldr_fxt();
+	@Before public void init() {fxt.Clear();}
+	@Test   public void Same() {
+		fxt.Init__tbl__old(Object_.Ary(1, "A")	, Object_.Ary(2, "B"));
+		fxt.Init__tbl__cur(Object_.Ary(1, "A")	, Object_.Ary(2, "B"));
+		fxt.Test__bld();
+	}
+	@Test   public void Update() {
+		fxt.Init__tbl__old(Object_.Ary(1, "A")	, Object_.Ary(2, "B"));
+		fxt.Init__tbl__cur(Object_.Ary(1, "A1")	, Object_.Ary(2, "B1"));
+		fxt.Test__bld("U|1|A1", "U|2|B1");
+	}
+	@Test   public void Insert() {
+		fxt.Init__tbl__old(Object_.Ary(1, "A"));
+		fxt.Init__tbl__cur(Object_.Ary(1, "A")	, Object_.Ary(2, "B"));
+		fxt.Test__bld("I|2|B");
+	}
+	@Test   public void Delete() {
+		fxt.Init__tbl__old(Object_.Ary(1, "A")	, Object_.Ary(2, "B"));
+		fxt.Init__tbl__cur(Object_.Ary(1, "A"));
+		fxt.Test__bld("D|2");
+	}
+	@Test   public void Basic() {
+		fxt.Init__tbl__old
+		( Object_.Ary(1, "A")
+		, Object_.Ary(2, "B")
+		, Object_.Ary(3, "C")
+		);
+		fxt.Init__tbl__cur
+		( Object_.Ary(1, "A")
+		, Object_.Ary(2, "B1")
+		, Object_.Ary(4, "D")
+		);			
+		fxt.Test__bld("U|2|B1", "D|3", "I|4|D");
+	}
+}
+class Gfdb_diff_bldr_fxt {
+	private final    Gfdb_diff_bldr bldr = new Gfdb_diff_bldr();
+	private final    Db_conn old_conn, new_conn;
+	private final    Gfdb_diff_tbl tbl;
+	private final    Gfdb_diff_wkr__test wkr = new Gfdb_diff_wkr__test();
+	private final    Dbmeta_fld_itm[] flds_ary;
+	private final    String tbl_name = "tbl";
+	private final    Gdif_bldr_ctx ctx = new Gdif_bldr_ctx();
+	public Gfdb_diff_bldr_fxt() {
+		old_conn = Db_conn_utl.Conn__new("old_db");
+		new_conn = Db_conn_utl.Conn__new("new_db");
+		this.flds_ary = new Dbmeta_fld_itm[] {Dbmeta_fld_itm.new_int("id").Primary_y_(), Dbmeta_fld_itm.new_str("val", 255)};
+		tbl = Gfdb_diff_tbl.New(Dbmeta_tbl_itm.New(tbl_name, flds_ary));
+		bldr.Init(wkr);
+	}
+	public void Clear() {
+		ctx.Clear();
+		old_conn.Meta_tbl_delete("tbl");
+		new_conn.Meta_tbl_delete("tbl");
+	}
+	public void Init__tbl__old(Object[]... rows) {Db_conn_utl.Tbl__new(old_conn, "tbl", flds_ary, rows);}
+	public void Init__tbl__cur(Object[]... rows) {Db_conn_utl.Tbl__new(new_conn, "tbl", flds_ary, rows);}
+	public void Test__bld(String... expd) {
+		bldr.Compare(ctx, tbl, old_conn, new_conn);
+		Tfds.Eq_ary_str(expd, wkr.To_str_ary());
+	}
+}
+class Gfdb_diff_wkr__test implements Gfdb_diff_wkr {
+	private final    List_adp list = List_adp_.New();
+	private final    Bry_bfr bfr = Bry_bfr_.New();
+	private Db_rdr old_rdr, new_rdr;
+	public void Init_rdrs(Gdif_bldr_ctx ctx, Gfdb_diff_tbl tbl, Db_rdr old_rdr, Db_rdr new_rdr) {
+		this.old_rdr = old_rdr; this.new_rdr = new_rdr;
+	}
+	public void Term_tbls() {}
+	public void Handle_same() {
+		String old_val = old_rdr.Read_str("val");
+		String new_val = new_rdr.Read_str("val");
+		if (!String_.Eq(old_val, new_val))
+			list.Add(bfr.Add_str_a7("U").Add_byte_pipe().Add_obj(old_rdr.Read_obj("id")).Add_byte_pipe().Add_str_a7(new_val).To_str_and_clear());
+	}
+	public void Handle_old_missing() {
+		String new_val = new_rdr.Read_str("val");
+		list.Add(bfr.Add_str_a7("I").Add_byte_pipe().Add_obj(new_rdr.Read_obj("id")).Add_byte_pipe().Add_str_a7(new_val).To_str_and_clear());
+	}
+	public void Handle_new_missing() {
+		list.Add(bfr.Add_str_a7("D").Add_byte_pipe().Add_obj(old_rdr.Read_obj("id")).To_str_and_clear());
+	}
+	public String[] To_str_ary() {return list.To_str_ary_and_clear();}
+}

140_dbs/src/gplx/dbs/diffs/builds/Gfdb_diff_rdr_comparer.java

@@ -13,3 +13,52 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.diffs.builds; import gplx.*; import gplx.dbs.*; import gplx.dbs.diffs.*;
+class Gfdb_diff_rdr_comparer {
+	private Db_rdr old_rdr, new_rdr;
+	private boolean old_rdr_move, new_rdr_move;
+	private boolean old_rdr_done, new_rdr_done;
+	private Dbmeta_fld_itm[] key_flds; private int key_flds_len;
+	public void Init_rdrs(Gfdb_diff_tbl tbl, Db_rdr old_rdr, Db_rdr new_rdr) {
+		this.old_rdr = old_rdr; this.new_rdr = new_rdr;
+		this.old_rdr_move = new_rdr_move = Bool_.Y;
+		this.old_rdr_done = new_rdr_done = Bool_.N;
+		this.key_flds = tbl.Keys; key_flds_len = key_flds.length;
+	}
+	public int Compare() {
+		if (old_rdr_move) {
+			old_rdr_move = old_rdr.Move_next();
+			if (!old_rdr_move) old_rdr_done = true;
+		}
+		if (new_rdr_move) {
+			new_rdr_move = new_rdr.Move_next();
+			if (!new_rdr_move) new_rdr_done = true;
+		}
+		if		(old_rdr_done && new_rdr_done)	return Gfdb_diff_rdr_comparer.Rslt__done;
+		else if	(old_rdr_done)					{new_rdr_move = true; return Gfdb_diff_rdr_comparer.Rslt__old_missing;}
+		else if (new_rdr_done)					{old_rdr_move = true; return Gfdb_diff_rdr_comparer.Rslt__new_missing;}
+		else {
+			int comp = Gfdb_rdr_utl_.Compare(key_flds, key_flds_len, old_rdr, new_rdr);
+			switch (comp) {
+				case CompareAble_.Same:			// old == cur; move both
+					old_rdr_move = new_rdr_move = true;
+					return Gfdb_diff_rdr_comparer.Rslt__same;
+				case CompareAble_.Less:			// old < cur; EX: old == 2; cur == 3
+					old_rdr_move = true;
+					new_rdr_move = false;
+					return Gfdb_diff_rdr_comparer.Rslt__new_missing;
+				case CompareAble_.More:			// old > cur; EX: old == 4; cur == 3
+					old_rdr_move = false;
+					new_rdr_move = true;
+					return Gfdb_diff_rdr_comparer.Rslt__old_missing;
+				default: throw Err_.new_unhandled(comp);
+			}
+		}
+	}
+	public static final int 
+	  Rslt__same		= 0
+	, Rslt__old_missing	= 1
+	, Rslt__new_missing	= 2
+	, Rslt__done		= 3
+	;
+}

140_dbs/src/gplx/dbs/diffs/builds/Gfdb_diff_wkr.java

@@ -13,3 +13,11 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.diffs.builds; import gplx.*; import gplx.dbs.*; import gplx.dbs.diffs.*;
+public interface Gfdb_diff_wkr {
+	void Init_rdrs(Gdif_bldr_ctx ctx, Gfdb_diff_tbl tbl, Db_rdr old_rdr, Db_rdr new_rdr);
+	void Term_tbls();
+	void Handle_same();
+	void Handle_old_missing();
+	void Handle_new_missing();
+}

140_dbs/src/gplx/dbs/diffs/builds/Gfdb_diff_wkr__db.java

@@ -13,3 +13,75 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.diffs.builds; import gplx.*; import gplx.dbs.*; import gplx.dbs.diffs.*;
+import gplx.dbs.metas.*; import gplx.dbs.diffs.itms.*;
+public class Gfdb_diff_wkr__db implements Gfdb_diff_wkr {
+	private Dbmeta_fld_itm[] val_flds; private int val_flds_len;
+	private Gfdb_diff_tbl tbl; private Db_rdr old_rdr, new_rdr;
+	private Gdif_bldr_ctx ctx;
+	private Db_conn dif_conn; private Db_stmt stmt;
+	private int uid, prog_interval, prog_count;
+	private boolean cmd_create;
+	public void Init_conn(Gdif_db dif_db, int prog_interval) {this.dif_conn = dif_db.Conn(); this.prog_interval = prog_interval;}
+	public void Init_rdrs(Gdif_bldr_ctx ctx, Gfdb_diff_tbl tbl, Db_rdr old_rdr, Db_rdr new_rdr) {
+		this.ctx = ctx; this.tbl = tbl; this.old_rdr = old_rdr; this.new_rdr = new_rdr;
+		this.val_flds = tbl.Vals; val_flds_len = val_flds.length;
+		this.uid = 0; this.prog_count = 0;
+
+		String dif_tbl = tbl.Name; Dbmeta_fld_itm[] dif_flds = Gfdb_diff_wkr__db_.New_dif_flds(tbl.Flds);
+		if (!dif_conn.Meta_tbl_exists(dif_tbl)) dif_conn.Meta_tbl_create(Dbmeta_tbl_itm.New(dif_tbl, dif_flds));
+		this.stmt = dif_conn.Stmt_insert(dif_tbl, Gfdb_diff_wkr__db_.To_str_ary(dif_flds));
+		dif_conn.Txn_bgn("dif_db_tbl_" + dif_tbl);
+		cmd_create = true;
+	}
+	public void Term_tbls() {
+		dif_conn.Txn_end();
+	}
+	public void Handle_old_missing() {Insert(Gdif_db_.Tid__insert, ++uid, new_rdr, tbl.Flds);}
+	public void Handle_new_missing() {Insert(Gdif_db_.Tid__delete, ++uid, old_rdr, tbl.Flds);}
+	public void Handle_same() {
+		if (Gfdb_rdr_utl_.Compare(val_flds, val_flds_len, old_rdr, new_rdr) != CompareAble_.Same)
+			Insert(Gdif_db_.Tid__update, ++uid, new_rdr, tbl.Flds);
+	}
+	private void Insert(byte dif_type, int uid, Db_rdr rdr, Dbmeta_fld_itm[] flds) {
+		if (cmd_create) {
+			cmd_create = false;
+			ctx.Cur_cmd = ctx.Core.New_cmd(ctx, Gdif_cmd_itm.Tid__data);
+			ctx.Cur_txn = ctx.Core.New_txn(ctx, ctx.Cur_cmd.Cmd_id, Gdif_txn_itm.Owner_txn__null);
+		}
+		stmt.Clear();
+		stmt.Val_int	(Gdif_db_.Fld__dif_txn		, ctx.Cur_txn.Txn_id)
+			.Val_int	(Gdif_db_.Fld__dif_uid		, uid)
+			.Val_int	(Gdif_db_.Fld__dif_type		, dif_type)
+			.Val_int	(Gdif_db_.Fld__dif_db_src	, -1)
+			.Val_int	(Gdif_db_.Fld__dif_db_trg	, -1);
+		Gfdb_rdr_utl_.Stmt_args(stmt, flds, 0, flds.length, rdr);
+		stmt.Exec_insert();
+		if ((++prog_count % prog_interval) == 0) dif_conn.Txn_sav();
+	}
+}
+class Gfdb_diff_wkr__db_ {
+	public static Dbmeta_fld_itm[] New_dif_flds(Dbmeta_fld_itm[] cur_flds) {
+		int len = cur_flds.length;
+		int sys_flds = 5;
+		Dbmeta_fld_itm[] rv = new Dbmeta_fld_itm[len + sys_flds];
+		rv[0] = Dbmeta_fld_itm.new_int	(Gdif_db_.Fld__dif_txn);
+		rv[1] = Dbmeta_fld_itm.new_int	(Gdif_db_.Fld__dif_uid);
+		rv[2] = Dbmeta_fld_itm.new_byte	(Gdif_db_.Fld__dif_type);
+		rv[3] = Dbmeta_fld_itm.new_int	(Gdif_db_.Fld__dif_db_trg);
+		rv[4] = Dbmeta_fld_itm.new_int	(Gdif_db_.Fld__dif_db_src);
+		for (int i = 0; i < len; ++i) {
+			Dbmeta_fld_itm cur_fld = cur_flds[i];
+			Dbmeta_fld_itm dif_fld = new Dbmeta_fld_itm(cur_fld.Name(), cur_fld.Type());
+			rv[i + sys_flds] = dif_fld;
+		}
+		return rv;
+	}
+	public static String[] To_str_ary(Dbmeta_fld_itm[] ary) {
+		int len = ary.length;
+		String[] rv = new String[len];
+		for (int i = 0; i < len; ++i)
+			rv[i] = ary[i].Name();
+		return rv;
+	}
+}

140_dbs/src/gplx/dbs/diffs/cmds/Gfdb_diff_cmd.java

@@ -13,3 +13,291 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.diffs.cmds; import gplx.*; import gplx.dbs.*; import gplx.dbs.diffs.*;
+import gplx.core.srls.*; import gplx.core.brys.fmtrs.*;
+import gplx.dbs.metas.*;
+interface Gfdb_diff_cmd {
+	void Merge_undo();
+	void Merge_exec();		
+}
+class Gfdb_diff_ctx implements Gfo_srl_ctx {
+	public Gfo_srl_mgr_wtr Wtr_bgn(String key) {return null;}
+	public Gfo_srl_mgr_rdr Rdr_bgn(String key) {return null;}
+	public Dbmeta_dat_mgr Rdr_subs(String key) {return null;}
+	public Dbmeta_tbl_itm Tbls__get(String key) {return null;}
+}
+class Gfo_srl_mgr_rdr__defn {
+	public String Tbl = null;
+	public String[] Select_crt_cols = null;
+	public String[] Delete_crt_cols = null;
+}
+class Gfo_srl_mgr_rdr__db {
+	public Object	Get_subs	(Gfo_srl_ctx ctx, Gfo_srl_itm owner, Gfo_srl_itm proto, String defn_key, Dbmeta_dat_mgr crt_mgr) {
+		List_adp list = List_adp_.New();
+
+		Gfo_srl_mgr_rdr__defn defn = new Gfo_srl_mgr_rdr__defn();	// Get(key)
+		Db_conn conn = Db_conn_.Noop;
+		Db_stmt select = conn.Stmt_select(defn.Tbl, Dbmeta_fld_itm.Str_ary_empty, defn.Select_crt_cols);
+		int crt_len = crt_mgr.Len();
+		for (int i = 0; i < crt_len; ++i) {
+			Dbmeta_dat_itm crt = crt_mgr.Get_at(i);
+			switch (crt.Tid) {
+				case Dbmeta_fld_tid.Tid__int: select.Crt_int(crt.Key, Int_.Cast(crt.Val)); break;
+			}				
+		}
+		Db_rdr rdr = select.Exec_select__rls_manual();
+		while (rdr.Move_next()) {
+			Gfo_srl_itm sub = proto.Make_new(ctx);
+			list.Add(sub);
+			sub.Load(ctx, owner, null);
+		}
+		rdr.Rls();
+
+		return list.To_ary_and_clear(proto.getClass());
+	}
+	public void	Set_subs	(Gfo_srl_ctx ctx, Gfo_srl_itm owner, Gfo_srl_itm proto, Gfo_srl_itm[] subs_ary, String defn_key, Dbmeta_dat_mgr crt_mgr) {
+		Gfo_srl_mgr_rdr__defn defn = new Gfo_srl_mgr_rdr__defn();	// Get(key)
+		Db_conn conn = Db_conn_.Noop;
+		Db_stmt delete = conn.Stmt_delete(defn.Tbl, defn.Delete_crt_cols);
+		int crt_len = crt_mgr.Len();
+		for (int i = 0; i < crt_len; ++i) {
+			Dbmeta_dat_itm crt = crt_mgr.Get_at(i);
+			switch (crt.Tid) {
+				case Dbmeta_fld_tid.Tid__int: delete.Crt_int(crt.Key, Int_.Cast(crt.Val)); break;
+			}				
+		}
+		delete.Exec_delete();
+
+		int subs_len = subs_ary.length;
+		for (int i = 0; i < subs_len; ++i) {
+			Gfo_srl_itm itm = subs_ary[i];
+			itm.Save(ctx, owner, null);
+		}
+	}
+}
+class Gfdb_diff_cmd__idx__delete {
+	public Gfdb_diff_cmd__idx__delete(Dbmeta_idx_itm old) {this.Old = old;}
+	public final    Dbmeta_idx_itm Old;
+}
+class Gfdb_diff_cmd__idx__modify {
+	public Gfdb_diff_cmd__idx__modify(Dbmeta_idx_itm old, Dbmeta_idx_itm cur) {this.Old = old; this.Cur = cur;}
+	public final    Dbmeta_idx_itm Old;
+	public final    Dbmeta_idx_itm Cur;
+}
+class Gfdb_diff_txn {
+	public int Id = 0;
+}
+class Gfdb_diff_cmd__fld__create {
+	public Gfdb_diff_cmd__fld__create(Dbmeta_fld_itm cur) {this.cur = cur;}
+	private Dbmeta_fld_itm cur;
+	public void Save(Gfo_srl_ctx ctx, Gfo_srl_itm owner) {
+		Gfo_srl_mgr_wtr wtr = ctx.Wtr_bgn("cmd.fld");
+		wtr.Set_int		("txn_id"		, ((Gfdb_diff_txn)owner).Id);
+		wtr.Set_str		("name"			, cur.Name());
+		wtr.Set_int		("type_tid"		, cur.Type().Tid_ansi());
+		wtr.Set_int		("type_len_1"	, cur.Type().Len_1());
+		wtr.Set_int		("type_len_2"	, cur.Type().Len_2());
+		wtr.Set_bool	("primary"		, cur.Primary());
+		wtr.Set_int		("nullable"		, cur.Nullable_tid());
+		wtr.Set_str		("dflt"			, Object_.Xto_str_or(cur.Default(), null));
+		wtr.Itm_end();
+	}
+	public void Load(Gfo_srl_ctx ctx, Gfo_srl_itm owner) {
+		Gfo_srl_mgr_rdr rdr = ctx.Rdr_bgn("cmd.fld");
+		String name = rdr.Get_str("name");
+		int type_tid = rdr.Get_int("type_tid");
+		int type_len_1 = rdr.Get_int("type_len_1");
+		// int type_len_2 = rdr.Get_int("type_len_2");
+		boolean primary = rdr.Get_bool("primary");
+		int nullable_tid = rdr.Get_int("nullable");
+		String dflt_str = rdr.Get_str("dflt");
+		cur = new Dbmeta_fld_itm(name, Dbmeta_fld_tid.New(type_tid, type_len_1));
+		cur.Nullable_tid_(nullable_tid);
+		if (primary) cur.Primary_y_();
+		if (dflt_str != null) cur.Default_(dflt_str);
+		rdr.Itm_end();
+//			Gfdb_diff_cmd__idx__create idx = ((Gfdb_diff_cmd__idx__create)owner);			
+//			Dbmeta_tbl_itm tbl = ((Gfdb_diff_ctx)ctx).Tbls__get(idx.cur.Tbl());
+//			Dbmeta_fld_tid tid = tbl.Flds().Get_by(name).Type();
+	}
+}
+class Gfdb_diff_cmd__fld__delete {
+	public Gfdb_diff_cmd__fld__delete(Dbmeta_fld_itm old) {this.Old = old;}
+	public final    Dbmeta_fld_itm Old;
+}
+class Gfdb_diff_cmd__fld__modify {
+	public Gfdb_diff_cmd__fld__modify(Dbmeta_fld_itm old, Dbmeta_fld_itm cur) {this.Old = old; this.Cur = cur;}
+	public final    Dbmeta_fld_itm Old;
+	public final    Dbmeta_fld_itm Cur;
+}
+class Gfdb_diff_cmd__tbl__create {
+	public Gfdb_diff_cmd__tbl__create(Dbmeta_tbl_itm cur) {this.Cur = cur;}
+	public final    Dbmeta_tbl_itm Cur;
+}
+class Gfdb_diff_cmd__tbl__delete {
+	public Gfdb_diff_cmd__tbl__delete(Dbmeta_tbl_itm old) {this.Old = old;}
+	public final    Dbmeta_tbl_itm Old;
+}
+class Gfdb_diff_cmd_bldr {
+	public void Chk_tbls(List_adp rv, Dbmeta_tbl_mgr old_tbls, Dbmeta_tbl_mgr cur_tbls) {
+		int cur_tbls_len = cur_tbls.Len();
+		for (int i = 0; i < cur_tbls_len; ++i) {
+			Dbmeta_tbl_itm cur_tbl = cur_tbls.Get_at(i);
+			Dbmeta_tbl_itm old_tbl = old_tbls.Get_by(cur_tbl.Name());
+			if (old_tbl == null)
+				rv.Add(new Gfdb_diff_cmd__tbl__create(cur_tbl));
+			else {
+				Chk_idxs(rv, old_tbl, cur_tbl);
+				Chk_flds(rv, old_tbl, cur_tbl);
+				// Chk_data?
+			}
+		}
+		int old_tbls_len = old_tbls.Len();
+		for (int i = 0; i < old_tbls_len; ++i) {
+			Dbmeta_tbl_itm old_tbl = old_tbls.Get_at(i);
+			Dbmeta_tbl_itm cur_tbl = cur_tbls.Get_by(old_tbl.Name());
+			if (cur_tbl == null)
+				rv.Add(new Gfdb_diff_cmd__tbl__delete(old_tbl));
+		}
+	}
+	public void Chk_idxs(List_adp rv, Dbmeta_tbl_itm old_tbl, Dbmeta_tbl_itm cur_tbl) {
+		Dbmeta_idx_mgr old_idxs = old_tbl.Idxs(), cur_idxs = cur_tbl.Idxs();
+		int cur_idxs_len = cur_idxs.Len();
+		for (int i = 0; i < cur_idxs_len; ++i) {
+			Dbmeta_idx_itm cur_idx = cur_idxs.Get_at(i);
+			Dbmeta_idx_itm old_idx = old_idxs.Get_by(cur_idx.Name());
+			if (old_idx == null)
+				rv.Add(new Gfdb_diff_cmd__idx__create(cur_idx));
+			else
+				if (!cur_idx.Eq(old_idx))
+					rv.Add(new Gfdb_diff_cmd__idx__modify(old_idx, cur_idx));
+		}
+		int old_idxs_len = old_idxs.Len();
+		for (int i = 0; i < old_idxs_len; ++i) {
+			Dbmeta_idx_itm old_idx = old_idxs.Get_at(i);
+			Dbmeta_idx_itm cur_idx = cur_idxs.Get_by(old_idx.Name());
+			if (cur_idx == null)
+				rv.Add(new Gfdb_diff_cmd__idx__delete(old_idx));
+		}
+	}
+	public void Chk_flds(List_adp rv, Dbmeta_tbl_itm old_tbl, Dbmeta_tbl_itm cur_tbl) {
+		Dbmeta_fld_mgr old_flds = old_tbl.Flds(), cur_flds = cur_tbl.Flds();
+		int cur_flds_len = cur_flds.Len();
+		for (int i = 0; i < cur_flds_len; ++i) {
+			Dbmeta_fld_itm cur_fld = cur_flds.Get_at(i);
+			Dbmeta_fld_itm old_fld = old_flds.Get_by(cur_fld.Name());
+			if (old_fld == null)
+				rv.Add(new Gfdb_diff_cmd__fld__create(cur_fld));
+			else
+				if (!cur_fld.Eq(old_fld))
+					rv.Add(new Gfdb_diff_cmd__fld__modify(old_fld, cur_fld));
+		}
+		int old_flds_len = old_flds.Len();
+		for (int i = 0; i < old_flds_len; ++i) {
+			Dbmeta_fld_itm old_fld = old_flds.Get_at(i);
+			Dbmeta_fld_itm cur_fld = cur_flds.Get_by(old_fld.Name());
+			if (cur_fld == null)
+				rv.Add(new Gfdb_diff_cmd__fld__delete(old_fld));
+		}
+	}
+}
+class Gfdb_diff_cmd__insert {
+//      else if I
+//        // txn_bgn
+//        // audit
+//        INSERT INTO db_temp.page (diff_type, diff, *)
+//        SELECT 'D', d.page_id, *
+//        FROM   db_diff.page d
+//               JOIN db_main.page m ON d.page_id = m.page_id
+//        WHERE  d.diff_type = 0
+//        AND    d.diff_idx BETWEEN lo and hi
+//        
+//        // update
+//        INSERT INTO db_main.page
+//        SELECT  d.page_title
+//        FROM    db_diff.page d
+//                JOIN db_main.page m        
+//        // txn_end
+	private Db_conn conn;
+	private String exec_sql;
+	public void Init(Db_conn main_conn, Db_conn diff_conn, Db_conn temp_conn, Gfdb_diff_tbl tbl) {
+		this.conn = temp_conn;
+		this.exec_sql = "";
+//			this.exec_sql = String_.Format(String_.Concat_lines_nl_skip_last
+//			( "INSERT INTO db_curr.{tbl}"
+//			), Gfdb_diff_cmd_ctx.Alias__curr);
+	}
+	public void Merge_exec() {
+		conn.Exec_sql(exec_sql);
+	}
+}
+class Gfdb_diff_cmd_sql_bldr {
+	private final    Bry_fmtr fmtr = Bry_fmtr.new_();
+	private final    Bry_bfr tmp_bfr = Bry_bfr_.New();
+	public void Bld_insert(Bry_bfr bfr, String tbl_name, String[] keys, String[] vals, int rng_bgn, int rng_end) {
+		fmtr.Fmt_(Insert__fmt).Keys_(Insert__keys);
+		fmtr.Bld_bfr_many(bfr, tbl_name, Bld_flds(tmp_bfr, ", ", "d.", keys, vals), Bld_join(keys), rng_bgn, rng_end);
+	}
+	public void Bld_update(Bry_bfr bfr, String tbl_name, String[] keys, String[] vals, int rng_bgn, int rng_end) {
+		fmtr.Fmt_(Update__fmt).Keys_(Update__keys);
+		fmtr.Bld_bfr_many(bfr, tbl_name, Bld_flds(tmp_bfr, ", ", "d.", keys, vals), Bld_join(keys), rng_bgn, rng_end);
+	}
+	public void Bld_delete(Bry_bfr bfr, String tbl_name, String[] keys, int rng_bgn, int rng_end) {
+		fmtr.Fmt_(Delete__fmt).Keys_(Delete__keys);
+		fmtr.Bld_bfr_many(bfr, tbl_name, Bld_flds(tmp_bfr, " || '|' || ", "", keys, String_.Ary_empty), Bld_flds(tmp_bfr, " || '|' || ", "k.", keys, String_.Ary_empty), Bld_join(keys), rng_bgn, rng_end);
+	}
+	private static String Bld_flds(Bry_bfr tmp_bfr, String dlm, String alias, String[] keys, String[] vals) {
+		int keys_len = keys.length;
+		for (int i = 0; i < keys_len; ++i) {
+			String key = keys[i];
+			if (i != 0) tmp_bfr.Add_str_a7(dlm);
+			tmp_bfr.Add_str_a7(alias).Add_str_a7(key);
+		}
+		int flds_len = vals.length;
+		for (int i = 0; i < flds_len; ++i) {
+			String val = vals[i];
+			tmp_bfr.Add_str_a7(dlm);
+			tmp_bfr.Add_str_a7(alias).Add_str_a7(val);
+		}
+		return tmp_bfr.To_str_and_clear();
+	}
+	private String Bld_join(String[] keys) {
+		int len = keys.length;
+		for (int i = 0; i < len; ++i) {
+			String key = keys[i];
+			tmp_bfr.Add_str_a7(i == 0 ? " ON " : " AND ");
+			tmp_bfr.Add_str_a7("k.").Add_str_a7(key).Add_str_a7(" = ");
+			tmp_bfr.Add_str_a7("d.").Add_str_a7(key);
+		}
+		return tmp_bfr.To_str_and_clear();
+	}
+	private static final    String[] Insert__keys = String_.Ary("tbl", "flds", "join", "rng_bgn", "rng_end");
+	private static final    String Insert__fmt = String_.Concat_lines_nl_skip_last
+	( "INSERT  INTO db_curr.~{tbl}"
+	, "SELECT  ~{flds}"
+	, "FROM    db_temp.~{tbl}_pkey k"
+	, "        JOIN db_diff.~{tbl} d~{join}"
+	, "WHERE   k.diff_type = 1"
+	, "AND     k.diff_uid BETWEEN ~{rng_bgn} AND ~{rng_end};"
+	);
+	private static final    String[] Update__keys = String_.Ary("tbl", "flds", "join", "rng_bgn", "rng_end");
+	private static final    String Update__fmt = String_.Concat_lines_nl_skip_last
+	( "REPLACE INTO db_curr.~{tbl}" 
+	, "SELECT  ~{flds}"
+	, "FROM    db_temp.~{tbl}_pkey k"
+	, "        JOIN db_diff.~{tbl} d~{join}"
+	, "WHERE   k.diff_type = 2"
+	, "AND     k.diff_uid BETWEEN ~{rng_bgn} AND ~{rng_end};"
+	);
+	private static final    String[] Delete__keys = String_.Ary("tbl", "pkey_where", "pkey_select", "join", "rng_bgn", "rng_end");
+	private static final    String Delete__fmt = String_.Concat_lines_nl_skip_last
+	( "DELETE  db_curr.~{tbl}"
+	, "WHERE   ~{pkey_where} IN"
+	, "(       SELECT  ~{pkey_select}"
+	, "        FROM    db_temp.~{tbl}_pkey k"
+	, "                JOIN db_diff.~{tbl} d~{join}"
+	, "        WHERE   k.diff_type = 0"
+	, "        AND     k.diff_uid BETWEEN ~{rng_bgn} AND ~{rng_end}"
+	, ");"
+	);
+}

140_dbs/src/gplx/dbs/diffs/cmds/Gfdb_diff_cmd__idx__create.java

@@ -13,3 +13,103 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.diffs.cmds; import gplx.*; import gplx.dbs.*; import gplx.dbs.diffs.*;
+import gplx.core.srls.*; import gplx.dbs.metas.*;
+
+class Gfdb_diff_cmd__idx__create implements Gfo_srl_itm {
+	public Gfdb_diff_cmd__idx__create(Dbmeta_idx_itm cur) {this.cur = cur;}
+	public Dbmeta_idx_itm cur;
+	private Gfdb_diff_cmd__idx__fld[] flds = new Gfdb_diff_cmd__idx__fld[0];
+	public Gfo_srl_itm Make_new(Gfo_srl_ctx ctx) {return new Gfdb_diff_cmd__idx__create();} Gfdb_diff_cmd__idx__create() {} 
+	private int idx_uid;
+	// *_sdif_ddl_idx : txn_uid,idx_uid,idx_tbl,idx_name,idx_unique
+	public void Save(Gfo_srl_ctx ctx, Gfo_srl_itm owner, Gfo_srl_mgr_wtr wtr) {
+		wtr.Itm_bgn("idx");
+		wtr.Set_int		("idx_uid"		, idx_uid);
+		wtr.Set_str		("idx_tbl"		, cur.Tbl());
+		wtr.Set_str		("idx_name"		, cur.Name());
+		wtr.Set_bool	("idx_unique"	, cur.Unique());
+		wtr.Set_subs	(ctx, this, Gfdb_diff_cmd__idx__fld.Instance, flds, ctx.Rdr_subs("idx_fld").Add_int("idx_uid", idx_uid));
+		wtr.Itm_end();
+	}
+	public void Load(Gfo_srl_ctx ctx, Gfo_srl_itm owner, Gfo_srl_mgr_rdr rdr) {
+		rdr.Itm_bgn("idx");
+		this.idx_uid	= rdr.Get_int		("idx_uid");
+		String tbl		= rdr.Get_str		("idx_tbl");
+		String name		= rdr.Get_str		("idx_name");
+		boolean unique		= rdr.Get_bool		("idx_unique");
+		this.flds = (Gfdb_diff_cmd__idx__fld[])rdr.Get_subs(ctx, this, Gfdb_diff_cmd__idx__fld.Instance, ctx.Rdr_subs("idx_fld").Add_int("idx_uid", idx_uid));
+		cur = new Dbmeta_idx_itm(unique, tbl, name, Dbmeta_idx_fld.Ary_empty);
+		rdr.Itm_end();
+	}
+	public void Exec(Db_conn conn) {
+		conn.Meta_idx_create(cur);
+	}
+}
+class Gfdb_diff_cmd__idx__fld implements Gfo_srl_itm {
+	public Gfdb_diff_cmd__idx__fld(Dbmeta_idx_fld cur) {this.cur = cur;}
+	private Dbmeta_idx_fld cur;
+	public Gfo_srl_itm Make_new(Gfo_srl_ctx ctx) {return new Gfdb_diff_cmd__idx__fld();} Gfdb_diff_cmd__idx__fld() {} 
+	// *_sdif_ddl_idx_fld : idx_uid,fld_order,fld_name,fld_asc
+	public void Save(Gfo_srl_ctx ctx, Gfo_srl_itm owner, Gfo_srl_mgr_wtr wtr) {
+		wtr.Itm_bgn("idx_fld");
+		wtr.Set_str		("fld_name"		, cur.Name);
+		wtr.Set_int		("fld_asc"		, cur.Sort_tid);
+		wtr.Itm_end();
+	}
+	public void Load(Gfo_srl_ctx ctx, Gfo_srl_itm owner, Gfo_srl_mgr_rdr rdr) {
+		rdr.Itm_bgn("idx_fld");
+		String name		= rdr.Get_str		("fld_name");
+		int sort_tid	= rdr.Get_int		("fld_sort");
+		cur = new Dbmeta_idx_fld(name, sort_tid);
+		rdr.Itm_end();
+	}
+
+        public static final    Gfdb_diff_cmd__idx__fld Instance = new Gfdb_diff_cmd__idx__fld();
+}
+//	class Gfdb_diff_cmd__tbl__fld : Gfo_srl_itm {
+//		public Gfdb_diff_cmd__tbl__fld(Dbmeta_fld_itm cur) {this.cur = cur;}
+//		private Dbmeta_fld_itm cur;
+//		public String Name;
+//		public int Type_tid;
+//		public int Len1;
+//		public int Len2;
+//		public int Nullable;
+//		public boolean Primary;
+//		public boolean Autonum;
+//
+//		public Gfo_srl_itm Make_new(Gfo_srl_ctx ctx) {return new Gfdb_diff_cmd__tbl__fld();} Gfdb_diff_cmd__tbl__fld() {} 
+//		// *_sdif_ddl_tbl_fld : tbl_uid,fld_idx,fld_name,fld_type,fld_len1, fld_len2, fld_nullable, fld_primary, fld_autonumber
+//		public void Save(Gfo_srl_ctx ctx, Gfo_srl_itm owner, Gfo_srl_mgr_wtr wtr) {
+//			wtr.Itm_bgn("tbl_fld");
+//			wtr.Set_str		("fld_name"		, cur.Name());
+//			wtr.Set_int		("fld_type"		, cur.Type().Tid_ansi());
+//			wtr.Set_int		("fld_len1"		, cur.Type().Len_1());
+//			wtr.Set_int		("fld_len2"		, cur.Type().Len_2());
+//			wtr.Set_int		("fld_nullable"	, cur.Nullable_tid());
+//			wtr.Set_bool	("fld_primary"	, cur.Primary());
+//			wtr.Set_bool	("fld_autonum"	, cur.Autonum());
+//			wtr.Set_str		("fld_dflt"		, Object_.Xto_str_or(cur.Default(), null));
+////			wtr.Set_int		("fld_asc"		, cur.Sort_tid);
+//			wtr.Itm_end();
+//		}
+//		public void Load(Gfo_srl_ctx ctx, Gfo_srl_itm owner, Gfo_srl_mgr_rdr rdr) {
+//			rdr.Itm_bgn("tbl_fld");
+//			String name = rdr.Get_str("name");
+//			int type_tid = rdr.Get_int("type_tid");
+//			int type_len_1 = rdr.Get_int("type_len_1");
+//			boolean primary = rdr.Get_bool("primary");
+//			int nullable_tid = rdr.Get_int("nullable");
+//			String dflt_str = rdr.Get_str("dflt");
+//			cur = new Dbmeta_fld_itm(name, Dbmeta_fld_tid.New(type_tid, type_len_1));
+//			cur.Nullable_tid_(nullable_tid);
+//			if (primary) cur.Primary_y_();
+//			if (dflt_str != null) cur.Default_(dflt_str);
+//			rdr.Itm_end();
+////			Gfdb_diff_cmd__idx__create idx = ((Gfdb_diff_cmd__idx__create)owner);			
+////			Dbmeta_tbl_itm tbl = ((Gfdb_diff_ctx)ctx).Tbls__get(idx.cur.Tbl());
+////			Dbmeta_fld_tid tid = tbl.Flds().Get_by(name).Type();
+//		}
+//
+//        public static final    Gfdb_diff_cmd__tbl__fld Instance = new Gfdb_diff_cmd__tbl__fld();
+//	}

140_dbs/src/gplx/dbs/diffs/cmds/Gfdb_diff_cmd_sql_bldr_tst.java

@@ -13,3 +13,57 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.diffs.cmds; import gplx.*; import gplx.dbs.*; import gplx.dbs.diffs.*;
+import org.junit.*;
+import gplx.dbs.*; import gplx.dbs.engines.mems.*;
+public class Gfdb_diff_cmd_sql_bldr_tst {
+	private final    Gfdb_diff_cmd_sql_bldr_fxt fxt = new Gfdb_diff_cmd_sql_bldr_fxt();
+	@Test   public void Insert() {
+		fxt.Test__insert("tbl1", String_.Ary("key1", "key2"), String_.Ary("fld1", "fld2"), 0, 99, String_.Concat_lines_nl_skip_last
+		( "INSERT  INTO db_curr.tbl1"
+		, "SELECT  d.key1, d.key2, d.fld1, d.fld2"
+		, "FROM    db_temp.tbl1_pkey k"
+		, "        JOIN db_diff.tbl1 d ON k.key1 = d.key1 AND k.key2 = d.key2"
+		, "WHERE   k.diff_type = 1"
+		, "AND     k.diff_uid BETWEEN 0 AND 99;"
+		));
+	}
+	@Test   public void Update() {
+		fxt.Test__update("tbl1", String_.Ary("key1", "key2"), String_.Ary("fld1", "fld2"), 0, 99, String_.Concat_lines_nl_skip_last
+		( "REPLACE INTO db_curr.tbl1"
+		, "SELECT  d.key1, d.key2, d.fld1, d.fld2"
+		, "FROM    db_temp.tbl1_pkey k"
+		, "        JOIN db_diff.tbl1 d ON k.key1 = d.key1 AND k.key2 = d.key2"
+		, "WHERE   k.diff_type = 2"
+		, "AND     k.diff_uid BETWEEN 0 AND 99;"
+		));
+	}
+	@Test   public void Delete() {
+		fxt.Test__delete("tbl1", String_.Ary("key1", "key2"), 0, 99, String_.Concat_lines_nl_skip_last
+		( "DELETE  db_curr.tbl1"
+		, "WHERE   key1 || '|' || key2 IN"
+		, "(       SELECT  k.key1 || '|' || k.key2"
+		, "        FROM    db_temp.tbl1_pkey k"
+		, "                JOIN db_diff.tbl1 d ON k.key1 = d.key1 AND k.key2 = d.key2"
+		, "        WHERE   k.diff_type = 0"
+		, "        AND     k.diff_uid BETWEEN 0 AND 99"
+		, ");"
+		));
+	}
+}
+class Gfdb_diff_cmd_sql_bldr_fxt {
+	private Gfdb_diff_cmd_sql_bldr bldr = new Gfdb_diff_cmd_sql_bldr();
+	private final    Bry_bfr bfr = Bry_bfr_.New();
+	public void Test__insert(String tbl_name, String[] keys, String[] flds, int rng_bgn, int rng_end, String expd) {
+		bldr.Bld_insert(bfr, tbl_name, keys, flds, 0, 99);
+		Tfds.Eq_str_lines(expd, bfr.To_str_and_clear());
+	}
+	public void Test__update(String tbl_name, String[] keys, String[] flds, int rng_bgn, int rng_end, String expd) {
+		bldr.Bld_update(bfr, tbl_name, keys, flds, 0, 99);
+		Tfds.Eq_str_lines(expd, bfr.To_str_and_clear());
+	}
+	public void Test__delete(String tbl_name, String[] keys, int rng_bgn, int rng_end, String expd) {
+		bldr.Bld_delete(bfr, tbl_name, keys, 0, 99);
+		Tfds.Eq_str_lines(expd, bfr.To_str_and_clear());
+	}
+}

140_dbs/src/gplx/dbs/diffs/itms/Gdif_cmd_itm.java

@@ -13,3 +13,15 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.diffs.itms; import gplx.*; import gplx.dbs.*; import gplx.dbs.diffs.*;
+public class Gdif_cmd_itm {
+	public Gdif_cmd_itm(int grp_id, int cmd_id, int tid) {
+		this.Grp_id = grp_id; this.Cmd_id = cmd_id; this.Tid = tid;
+	}
+	public final int Grp_id;
+	public final int Cmd_id;
+	public final int Tid;
+	public String Data;
+
+	public static final int Tid__data = 1;
+}

140_dbs/src/gplx/dbs/diffs/itms/Gdif_cmd_tbl.java

@@ -13,3 +13,29 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.diffs.itms; import gplx.*; import gplx.dbs.*; import gplx.dbs.diffs.*;
+public class Gdif_cmd_tbl implements Rls_able {
+	private String tbl_name = "gdif_cmd";
+	private String fld_grp_id, fld_cmd_id, fld_tid, fld_data;
+	private final    Dbmeta_fld_list flds = new Dbmeta_fld_list();
+	private final    Db_conn conn; private Db_stmt stmt_insert;
+	public Gdif_cmd_tbl(Db_conn conn) {
+		this.conn = conn;
+		fld_grp_id = flds.Add_int("grp_id"); fld_cmd_id = flds.Add_int("cmd_id"); fld_tid = flds.Add_int("tid"); fld_data = flds.Add_text("data");
+		conn.Rls_reg(this);
+	}
+	public void Create_tbl() {conn.Meta_tbl_create(Dbmeta_tbl_itm.New(tbl_name, flds, Dbmeta_idx_itm.new_unique_by_tbl(tbl_name, "main", fld_grp_id, fld_cmd_id)));}
+	public Gdif_cmd_itm Insert(int grp_id, int cmd_id, int tid, String data) {
+		if (stmt_insert == null) stmt_insert = conn.Stmt_insert(tbl_name, flds);
+		stmt_insert.Clear()
+		.Val_int(fld_grp_id		, grp_id)
+		.Val_int(fld_cmd_id		, cmd_id)
+		.Val_int(fld_tid		, tid)
+		.Val_str(fld_data		, data)
+		.Exec_insert();
+		return new Gdif_cmd_itm(grp_id, cmd_id, tid);
+	}
+	public void Rls() {
+		stmt_insert = Db_stmt_.Rls(stmt_insert);
+	}
+}

140_dbs/src/gplx/dbs/diffs/itms/Gdif_job_itm.java

@@ -13,3 +13,14 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.diffs.itms; import gplx.*; import gplx.dbs.*; import gplx.dbs.diffs.*;
+public class Gdif_job_itm {
+	public Gdif_job_itm(int id, String name, String made_by, DateAdp made_on) {
+		this.Id = id; this.Name = name; this.Made_by = made_by; this.Made_on = made_on;
+	}
+	public final int Id;
+	public final String Name;
+	public final String Made_by;
+	public final DateAdp Made_on;
+	public String Data;
+}

140_dbs/src/gplx/dbs/diffs/itms/Gdif_job_tbl.java

@@ -13,3 +13,32 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.diffs.itms; import gplx.*; import gplx.dbs.*; import gplx.dbs.diffs.*;
+public class Gdif_job_tbl implements Rls_able {
+	private String tbl_name = "gdif_job";
+	private String fld_job_id, fld_name, fld_made_by, fld_made_on, fld_data;
+	private final    Dbmeta_fld_list flds = new Dbmeta_fld_list();
+	private final    Db_conn conn; private Db_stmt stmt_insert;
+	public Gdif_job_tbl(Db_conn conn) {
+		this.conn = conn;
+		fld_job_id = flds.Add_int_pkey("job_id"); fld_name = flds.Add_str("name", 255); fld_made_by = flds.Add_str("made_by", 255); fld_made_on = flds.Add_date("made_on"); fld_data = flds.Add_text("data");
+		conn.Rls_reg(this);
+	}
+	public String Tbl_name() {return tbl_name;}
+	public String Fld_job_id() {return fld_job_id;}
+	public void Create_tbl() {conn.Meta_tbl_create(Dbmeta_tbl_itm.New(tbl_name, flds));}
+	public Gdif_job_itm Insert(int id, String name, String made_by, DateAdp made_on, String data) {
+		if (stmt_insert == null) stmt_insert = conn.Stmt_insert(tbl_name, flds);
+		stmt_insert.Clear()
+		.Val_int(fld_job_id		, id)
+		.Val_str(fld_name		, name)
+		.Val_str(fld_made_by	, made_by)
+		.Val_date(fld_made_on	, made_on)
+		.Val_str(fld_data		, data)
+		.Exec_insert();
+		return new Gdif_job_itm(id, name, made_by, made_on);
+	}
+	public void Rls() {
+		stmt_insert = Db_stmt_.Rls(stmt_insert);
+	}
+}

140_dbs/src/gplx/dbs/diffs/itms/Gdif_txn_itm.java

@@ -13,3 +13,15 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.diffs.itms; import gplx.*; import gplx.dbs.*; import gplx.dbs.diffs.*;
+public class Gdif_txn_itm {
+	public Gdif_txn_itm(int job_id, int txn_id, int cmd_id, int owner_txn) {
+		this.Job_id = job_id; this.Txn_id = txn_id; this.Cmd_id = cmd_id; this.Owner_txn = owner_txn;
+	}
+	public final int Job_id;
+	public final int Txn_id;
+	public final int Cmd_id;
+	public final int Owner_txn;
+
+	public static final int Owner_txn__null = 0;
+}

140_dbs/src/gplx/dbs/diffs/itms/Gdif_txn_tbl.java

@@ -13,3 +13,29 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.diffs.itms; import gplx.*; import gplx.dbs.*; import gplx.dbs.diffs.*;
+public class Gdif_txn_tbl implements Rls_able {
+	private String tbl_name = "gdif_txn";
+	private String fld_job_id, fld_txn_id, fld_cmd_id, fld_owner_txn;
+	private final    Dbmeta_fld_list flds = new Dbmeta_fld_list();
+	private final    Db_conn conn; private Db_stmt stmt_insert;
+	public Gdif_txn_tbl(Db_conn conn) {
+		this.conn = conn;
+		fld_job_id = flds.Add_int("job_id"); fld_txn_id = flds.Add_int("txn_id"); fld_cmd_id = flds.Add_int("cmd_id"); fld_owner_txn = flds.Add_int("owner_txn");
+		conn.Rls_reg(this);
+	}
+	public void Create_tbl() {conn.Meta_tbl_create(Dbmeta_tbl_itm.New(tbl_name, flds, Dbmeta_idx_itm.new_unique_by_tbl(tbl_name, "main", fld_job_id, fld_txn_id)));}
+	public Gdif_txn_itm Insert(int job_id, int txn_id, int cmd_id, int owner_txn) {
+		if (stmt_insert == null) stmt_insert = conn.Stmt_insert(tbl_name, flds);
+		stmt_insert.Clear()
+		.Val_int(fld_job_id		, job_id)
+		.Val_int(fld_txn_id		, txn_id)
+		.Val_int(fld_cmd_id		, cmd_id)
+		.Val_int(fld_owner_txn	, owner_txn)
+		.Exec_insert();
+		return new Gdif_txn_itm(job_id, txn_id, cmd_id, owner_txn);
+	}
+	public void Rls() {
+		stmt_insert = Db_stmt_.Rls(stmt_insert);
+	}
+}

140_dbs/src/gplx/dbs/engines/Db_engine.java

@@ -13,3 +13,37 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.engines; import gplx.*; import gplx.dbs.*;
+import gplx.core.stores.*; import gplx.dbs.metas.*; import gplx.dbs.sqls.*; import gplx.dbs.conn_props.*; import gplx.dbs.qrys.bats.*;
+public interface Db_engine {
+	String				Tid();
+	Db_conn_info		Conn_info();
+	Db_conn_props_mgr	Props();
+	Db_batch_mgr		Batch_mgr();
+	Sql_qry_wtr			Sql_wtr();
+	Db_engine			New_clone(Db_conn_info conn_info);
+	void				Conn_open();
+	void				Conn_term();
+	void				Txn_bgn(String name);		// NOTE: sqlite has different transaction semantics with SAVEPOINT
+	String				Txn_end();
+	void				Txn_cxl();
+	void				Txn_sav();
+	void				Meta_tbl_create(Dbmeta_tbl_itm meta);
+	void				Meta_tbl_delete(String tbl);
+	void				Meta_fld_append(String tbl, Dbmeta_fld_itm fld);
+	void				Meta_idx_create(Gfo_usr_dlg usr_dlg, Dbmeta_idx_itm... ary);
+	void				Meta_idx_delete(String idx);
+	Dbmeta_tbl_mgr		Meta_mgr();
+	boolean				Meta_tbl_exists(String tbl);
+	boolean				Meta_fld_exists(String tbl, String fld);
+	boolean				Meta_idx_exists(String idx);
+	Object				Exec_as_obj(Db_qry qry);
+	Db_rdr				Exec_as_rdr__rls_manual	(Object rdr_obj, String sql);				// Object o:ResultSet if desktop; Cursor if android
+	Db_rdr				Exec_as_rdr__rls_auto	(Db_stmt stmt, Object rdr_obj, String sql);	// Object o:ResultSet if desktop; Cursor if android
+	Db_stmt				Stmt_by_qry(Db_qry qry);
+	Object				Stmt_by_sql(String sql);
+	void				Env_db_attach(String alias, Db_conn conn);
+	void				Env_db_attach(String alias, Io_url db_url);
+	void				Env_db_detach(String alias);
+	DataRdr				New_rdr(java.sql.ResultSet rdr, String sql); 
+}

140_dbs/src/gplx/dbs/engines/Db_engine_sql_base.java

@@ -13,3 +13,127 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.engines; import gplx.*; import gplx.dbs.*;
+import java.sql.*; 
+import gplx.core.stores.*;
+import gplx.dbs.engines.*; import gplx.dbs.metas.*; import gplx.dbs.qrys.*; import gplx.dbs.sqls.*; import gplx.dbs.sqls.wtrs.*; import gplx.dbs.conn_props.*; import gplx.dbs.qrys.bats.*;
+public abstract class Db_engine_sql_base implements Db_engine {
+	@gplx.Internal protected void Ctor(Db_conn_info conn_info) {this.conn_info = conn_info;}
+	public abstract String		Tid();
+	public Db_conn_info			Conn_info() {return conn_info;} protected Db_conn_info conn_info;
+	public Db_conn_props_mgr	Props() {return props;} private final    Db_conn_props_mgr props = new Db_conn_props_mgr();
+	public Db_batch_mgr			Batch_mgr() {return batch_mgr;} private final    Db_batch_mgr batch_mgr = new Db_batch_mgr();
+	public abstract Sql_qry_wtr	Sql_wtr();
+	public abstract				Db_engine New_clone(Db_conn_info conn_info);
+	public Db_rdr				Exec_as_rdr__rls_manual(Object rdr_obj, String sql)				{return New_rdr(null, rdr_obj, sql);}
+	public Db_rdr				Exec_as_rdr__rls_auto(Db_stmt stmt, Object rdr_obj, String sql)	{return New_rdr(stmt, rdr_obj, sql);}
+	@gplx.Virtual public 			Db_rdr New_rdr_clone() {return new Db_rdr__basic();}
+	@gplx.Virtual public Db_stmt		Stmt_by_qry(Db_qry qry) {return new Db_stmt_cmd(this, qry);}
+	@gplx.Virtual public void			Txn_bgn(String name)	{Exec_as_obj(Db_qry_sql.xtn_("BEGIN TRANSACTION;"));}
+	@gplx.Virtual public String		Txn_end()				{Exec_as_obj(Db_qry_sql.xtn_("COMMIT TRANSACTION;")); batch_mgr.Txn_end().Run(this); return "";}
+	@gplx.Virtual public void			Txn_cxl()				{Exec_as_obj(Db_qry_sql.xtn_("ROLLBACK TRANSACTION;"));}
+	@gplx.Virtual public void			Txn_sav() {
+		String txn_name = this.Txn_end();
+		this.Txn_bgn(txn_name);
+	}
+	public Object		Exec_as_obj(Db_qry qry) {
+		if (qry.Tid() == Db_qry_.Tid_flush) return null;	// ignore flush (delete-db) statements
+		String sql = this.Sql_wtr().To_sql_str(qry, false); // DBG: Tfds.Write(sql);
+		return qry.Exec_is_rdr() ? (Object)this.Exec_as_rdr(sql) : this.Exec_as_int(sql);
+	}
+	protected int Exec_as_int(String sql) {
+		try {
+			Statement cmd = New_stmt_exec(sql);	
+			return cmd.executeUpdate(sql);			
+		}
+		catch (Exception e) {throw Err_.new_exc(e, "db", "db.engine:exec failed", "url", conn_info.Db_api(), "sql", sql);}
+	}
+	private DataRdr Exec_as_rdr(String sql) {
+		try {
+			Statement cmd = New_stmt_exec(sql);	
+			cmd.execute(sql);										
+			ResultSet rdr = cmd.getResultSet();	
+			return New_rdr(rdr, sql);
+		}
+		catch (Exception e) {throw Err_.new_exc(e, "db", "db.engine:rdr failed", "url", conn_info.Db_api(), "sql", sql);}
+	}
+	public void Meta_tbl_create(Dbmeta_tbl_itm tbl) {Exec_as_int(tbl.To_sql_create(this.Sql_wtr()));				this.Meta_mgr().Load_all();}
+	public void Meta_tbl_delete(String tbl)			{Exec_as_int(this.Sql_wtr().Schema_wtr().Bld_drop_tbl(tbl));	this.Meta_mgr().Load_all();}
+	public void Meta_idx_create(Gfo_usr_dlg usr_dlg, Dbmeta_idx_itm... ary) {
+		int len = ary.length;
+		for (int i = 0; i < len; ++i) {
+			Dbmeta_idx_itm idx = ary[i];
+			usr_dlg.Plog_many("", "", "creating db index (please wait); db=~{0} idx=~{1}", conn_info.Database(), idx.Name());
+			Exec_as_int(idx.To_sql_create(Sql_wtr()));
+		}
+		this.Meta_mgr().Load_all();
+	}
+	@gplx.Virtual public void Meta_idx_delete(String idx) {
+		if (Meta_idx_exists(idx)) Exec_as_int("DROP INDEX " + idx);
+	}
+	public void Meta_fld_append(String tbl, Dbmeta_fld_itm fld) {
+		Gfo_usr_dlg_.Instance.Plog_many("", "", "adding column to table: db=~{0} tbl=~{1} fld=~{2}", conn_info.Database(), tbl, fld.Name());
+		try {
+			Exec_as_int(this.Sql_wtr().Schema_wtr().Bld_alter_tbl_add(tbl, fld));
+			Gfo_usr_dlg_.Instance.Plog_many("", "", "column added to table: db=~{0} tbl=~{1} fld=~{2}", conn_info.Database(), tbl, fld.Name());
+		}
+		catch (Exception e) {	// catch error if column already added to table
+			Gfo_usr_dlg_.Instance.Warn_many("", "", "column not added to table: db=~{0} tbl=~{1} fld=~{2} err=~{3}", conn_info.Database(), tbl, fld.Name(), Err_.Message_gplx_full(e));
+		}
+		this.Meta_mgr().Load_all();
+	}
+	@gplx.Virtual public boolean Meta_tbl_exists(String tbl)					{return false;}
+	@gplx.Virtual public boolean	Meta_fld_exists(String tbl, String fld)		{return false;}
+	@gplx.Virtual public boolean	Meta_idx_exists(String idx)					{return false;}
+	public abstract Dbmeta_tbl_mgr Meta_mgr();
+	@gplx.Virtual public void Env_db_attach(String alias, Io_url db_url)	{}
+	@gplx.Virtual public void Env_db_attach(String alias, Db_conn db_url)	{}
+	@gplx.Virtual public void	Env_db_detach(String alias)					{}
+	@gplx.Virtual public DataRdr New_rdr(ResultSet rdr, String sql)		{return gplx.core.stores.Db_data_rdr_.new_(rdr, sql);}
+	private Db_rdr New_rdr(Db_stmt stmt, Object rdr, String sql) {
+		Db_rdr__basic rv = (Db_rdr__basic)New_rdr_clone();	
+		rv.Ctor(stmt, (ResultSet)rdr, sql);	
+		return rv;
+	}
+	@gplx.Internal protected abstract Connection Conn_make();	
+	private		void Batch_mgr__conn_bgn() {batch_mgr.Conn_bgn().Run(this);}
+	private		void Batch_mgr__conn_end() {batch_mgr.Conn_end().Run(this);}
+	private void Conn_assert() {
+		this.connection = Conn_make();	// auto-open connection
+		Batch_mgr__conn_bgn();
+	}
+		protected Connection connection;
+	public void Conn_open() {connection = Conn_make();}
+	public void Conn_term() {
+		if (connection == null) return;	// connection never opened; just exit
+		this.Batch_mgr__conn_end();
+		try 	{connection.close();}
+		catch 	(Exception e) {throw Err_.new_exc(e, "db", "Conn_term failed", "url", conn_info.Raw());}
+		connection = null;
+	}
+	@Override public Object Stmt_by_sql(String sql) {
+		if (connection == null) Conn_assert();
+		try 	{return connection.prepareStatement(sql);}
+		catch 	(Exception e) {
+			throw Err_.new_exc(e, "db", "New_stmt_prep failed", "sql", sql);
+			}
+	}
+	private Statement New_stmt_exec(String sql) {
+		if (connection == null) Conn_assert();
+		try 	{return connection.createStatement();}
+		catch 	(Exception e) {throw Err_.new_exc(e, "db", "New_stmt_exec failed", "sql", sql);}
+	}
+	protected Connection Conn_make_by_url(String url, String uid, String pwd) {
+		try {return DriverManager.getConnection(url, uid, pwd);}
+		catch (SQLException e) {throw Err_.new_exc(e, "db", "connection open failed", "info", Conn_info().Raw());}
+	}
+	protected Connection Conn__new_by_url_and_props(String url, Keyval... props) {
+		try {
+			java.util.Properties properties = new java.util.Properties();
+			for (Keyval prop : props)
+				properties.setProperty(prop.Key(), prop.Val_to_str_or_empty());
+			return DriverManager.getConnection(url, properties);
+		}
+		catch (SQLException e) {throw Err_.new_exc(e, "db", "connection open failed", "info", Conn_info().Raw());}
+	}
+	}

140_dbs/src/gplx/dbs/engines/mems/Mem_conn_info.java

@@ -13,3 +13,18 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.engines.mems; import gplx.*; import gplx.dbs.*; import gplx.dbs.engines.*;
+public class Mem_conn_info extends Db_conn_info__base {
+	public Mem_conn_info(String raw, String db_api, String database) {super(raw, db_api, database);}
+	@Override public String Key() {return Tid_const;} public static final String Tid_const = "mem";
+	@Override public Db_conn_info New_self(String raw, Keyval_hash hash) {
+		return new Mem_conn_info(raw, raw, hash.Get_val_as_str_or_fail("database"));
+	}
+	public static Db_conn_info new_(String database) {
+		return Db_conn_info_.parse(Bld_raw
+		( "gplx_key", Tid_const
+		, "database", database
+		));
+	}
+        public static final Mem_conn_info Instance = new Mem_conn_info("", "", "");
+}

140_dbs/src/gplx/dbs/engines/mems/Mem_db_fxt.java

@@ -13,3 +13,60 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.engines.mems; import gplx.*; import gplx.dbs.*; import gplx.dbs.engines.*;
+class Mem_db_fxt {
+	public Mem_db_fxt() {
+		Io_mgr.Instance.InitEngine_mem();
+		Db_conn_bldr.Instance.Reg_default_mem();
+	}
+	public Db_conn			Make_conn(String url) {return Db_conn_bldr.Instance.Get_or_autocreate(Bool_.Y, Io_url_.mem_fil_(url));}
+	public Dbmeta_tbl_itm	Exec__create_tbl(Db_conn conn, String tbl, String... fld_names) {
+		Dbmeta_fld_list flds = new Dbmeta_fld_list();
+		int len = fld_names.length;
+		for (int i = 0; i < len; ++i)
+			flds.Add_str(fld_names[i], 255);
+		Dbmeta_tbl_itm rv = Dbmeta_tbl_itm.New(tbl, flds);
+		conn.Meta_tbl_create(rv);
+		return rv;
+	}
+	public void Exec__insert(Db_conn conn, String tbl_name, String[]... rows) {
+		Mem_engine engine = (Mem_engine)conn.Engine();
+		int rows_len = rows.length;
+		Mem_tbl tbl = engine.Tbls__get(tbl_name);
+		Dbmeta_fld_list flds_list = tbl.Meta().Flds().To_fld_list();
+		int flds_len = flds_list.Len();
+		Db_stmt stmt = conn.Stmt_insert(tbl_name, flds_list);
+		for (int i = 0; i < rows_len; ++i) {
+			stmt.Clear();
+			String[] row = rows[i];
+			for (int j = 0; j < flds_len; ++j)
+				stmt.Val_str(flds_list.Get_at(j).Name(), row[j]);
+			stmt.Exec_insert();
+		}
+	}
+	public void Test__select(Db_conn conn, Db_qry qry, String[]... expd) {
+		Db_stmt stmt = conn.Stmt_new(qry);
+		Db_rdr rdr = new Mem_exec_select((Mem_engine)conn.Engine()).Select((Mem_stmt)stmt);
+		List_adp actl_list = List_adp_.New();
+		Bry_bfr tmp_bfr = Bry_bfr_.New();
+		int expd_len = expd.length;
+		String[] expd_rows = new String[expd_len];
+		for (int i = 0; i < expd_len; ++i) {
+			String[] expd_row = expd[i];
+			for (int j = 0; j < expd_row.length; ++j) {
+				if (j != 0) tmp_bfr.Add_byte_pipe();
+				tmp_bfr.Add_str_u8(expd_row[j]);
+			}
+			expd_rows[i] = tmp_bfr.To_str_and_clear();
+		}
+		while (rdr.Move_next()) {
+			int fld_len = rdr.Fld_len();
+			for (int i = 0; i < fld_len; ++i) {
+				if (i != 0) tmp_bfr.Add_byte_pipe();
+				tmp_bfr.Add_obj_strict(rdr.Read_at(i));
+			}
+			actl_list.Add(tmp_bfr.To_str_and_clear());
+		}			
+		Tfds.Eq_ary(expd_rows, (String[])actl_list.To_ary_and_clear(String.class));
+	}
+}

140_dbs/src/gplx/dbs/engines/mems/Mem_engine.java

@@ -13,3 +13,58 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.engines.mems; import gplx.*; import gplx.dbs.*; import gplx.dbs.engines.*;
+import gplx.core.stores.*; import gplx.dbs.metas.*; import gplx.dbs.sqls.*; import gplx.dbs.conn_props.*; import gplx.dbs.qrys.bats.*;
+public class Mem_engine implements Db_engine {
+	private final    Hash_adp tbl_hash = Hash_adp_.New();
+	Mem_engine(Db_conn_info conn_info) {
+		this.conn_info = conn_info;
+		this.qry_runner = new Mem_exec_select(this);
+	}
+	public String				Tid() {return Mem_conn_info.Tid_const;}
+	public Db_conn_info			Conn_info() {return conn_info;} private Db_conn_info conn_info;
+	public Db_conn_props_mgr	Props() {return props;} private final    Db_conn_props_mgr props = new Db_conn_props_mgr();
+	public Db_batch_mgr			Batch_mgr() {return batch_mgr;} private final    Db_batch_mgr batch_mgr = new Db_batch_mgr();
+	public Mem_exec_select		Qry_runner() {return qry_runner;} private Mem_exec_select qry_runner;
+	public Sql_qry_wtr			Sql_wtr() {return sql_wtr;} private final    Sql_qry_wtr sql_wtr = Sql_qry_wtr_.New__basic();
+	public Db_engine			New_clone(Db_conn_info conn_info) {return new Mem_engine(conn_info);}
+	public Db_stmt				Stmt_by_qry(Db_qry qry) {return new Mem_stmt(this, qry);}
+	public Mem_tbl				Tbls__get(String name)	{return (Mem_tbl)tbl_hash.Get_by(name);}
+	public void					Tbls__del(String name)	{tbl_hash.Del(name);}
+	public void					Txn_bgn(String name)	{}//++txn_count;} private int txn_count = 0;
+	public String				Txn_end()				{return "";}// --txn_count; return "";}
+	public void					Txn_cxl()				{}//--txn_count;}
+	public void					Txn_sav()				{this.Txn_end(); this.Txn_bgn("");}
+	public Object				Exec_as_obj(Db_qry qry) {throw Err_.new_unimplemented();}
+	public void					Conn_open() {}
+	public void					Conn_term() {
+		// if (txn_count != 0) throw Err_.new_wo_type("Conn_term.txns still open", "txn_count", txn_count);	// IGNORE: causing test to fails; DATE:2016-03-30
+	}
+	public Db_rdr				Exec_as_rdr__rls_manual(Object rdr_obj, String sql) {throw Err_.new_unimplemented();}
+	public Db_rdr				Exec_as_rdr__rls_auto(Db_stmt stmt, Object rdr_obj, String sql) {throw Err_.new_unimplemented();}
+	public DataRdr				New_rdr(java.sql.ResultSet rdr, String sql) {throw Err_.new_unimplemented();} 
+	public Object				Stmt_by_sql(String sql) {throw Err_.new_unimplemented();}
+	public void					Meta_tbl_create(Dbmeta_tbl_itm meta) {
+		Mem_tbl mem_tbl = new Mem_tbl(meta);
+		tbl_hash.Add_if_dupe_use_nth(meta.Name(), mem_tbl);
+		meta_mgr.Add(meta);
+	}
+	public void					Meta_tbl_delete(String tbl_key) {
+		Mem_tbl tbl = (Mem_tbl)tbl_hash.Get_by(tbl_key);
+		if (tbl != null) tbl.rows.Clear();
+	}
+	public void					Meta_idx_create(Gfo_usr_dlg usr_dlg, Dbmeta_idx_itm... ary) {}	// TODO_OLD: implement unique index
+	public void					Meta_idx_delete(String idx) {}
+	public void					Meta_fld_append(String tbl, Dbmeta_fld_itm fld)	{}
+	public Dbmeta_tbl_mgr		Meta_mgr() {return meta_mgr;} private final    Dbmeta_tbl_mgr meta_mgr = new Dbmeta_tbl_mgr(Dbmeta_reload_cmd_.Noop);
+	public boolean					Meta_tbl_exists(String tbl)						{return tbl_hash.Has(tbl);}
+	public boolean					Meta_fld_exists(String tbl, String fld)			{
+		Mem_tbl mem_tbl = (Mem_tbl)tbl_hash.Get_by(tbl); if (mem_tbl == null) return false;
+		return mem_tbl.Meta().Flds().Has(fld);
+	}
+	public boolean					Meta_idx_exists(String idx)						{return false;}
+	public void					Env_db_attach(String alias, Db_conn conn)		{}
+	public void					Env_db_attach(String alias, Io_url db_url)		{}
+	public void					Env_db_detach(String alias)						{}
+        public static final    Mem_engine Instance = new Mem_engine(); Mem_engine() {}
+}

140_dbs/src/gplx/dbs/engines/mems/Mem_exec_select.java

@@ -13,3 +13,197 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.engines.mems; import gplx.*; import gplx.dbs.*; import gplx.dbs.engines.*;
+import gplx.core.criterias.*;
+import gplx.dbs.qrys.*; import gplx.dbs.sqls.itms.*;
+public class Mem_exec_select {
+	private final    Mem_engine engine;
+	private final    List_adp tmp_where_rows = List_adp_.New();
+	public Mem_exec_select(Mem_engine engine) {this.engine = engine;}
+	public Db_rdr Select(Mem_stmt stmt) {
+		Db_qry stmt_qry = stmt.Qry();
+		Mem_tbl tbl = engine.Tbls__get(stmt_qry.Base_table());
+		String[] select = null; Criteria where = null;
+		Db_qry__select_in_tbl qry = Db_qry__select_in_tbl.as_(stmt_qry);
+		Db_qry__select_cmd qry2 = null;
+		if (qry == null) {
+			qry2 = (Db_qry__select_cmd)stmt_qry;
+			select = Mem_exec_.Flds__to_str_ary(qry2.Cols().Flds);
+			where = qry2.Where_itm().Root;
+		}
+		else {
+			select = qry.Select_flds();
+			where = qry.Where();
+		}
+		Mem_stmt_args_.Fill(stmt.Stmt_args(), where);
+		Mem_row[] tbl_rows = (Mem_row[])tbl.rows.To_ary(Mem_row.class);
+		if (qry2 != null) {
+			tbl_rows = Mem_exec_.Rows__alias(tbl_rows, qry2.From().Base_tbl.Alias);
+			List_adp join_tbls = qry2.From().Tbls;
+			int join_tbls_len = join_tbls.Len();
+			for (int i = 1; i < join_tbls_len; ++i) {
+				Sql_tbl_itm join_tbl = (Sql_tbl_itm)join_tbls.Get_at(i);
+				Mem_row[] join_rows = (Mem_row[])engine.Tbls__get(join_tbl.Name).rows.To_ary(Mem_row.class);
+				join_rows = Mem_exec_.Rows__alias(join_rows, join_tbl.Alias);
+				tbl_rows = Mem_exec_.Rows__join(join_tbl.Join_tid, tbl_rows, join_rows, join_tbl.Alias, join_tbl.Join_flds);
+			}
+		}			
+		Mem_exec_.Where__filter(tmp_where_rows, tbl_rows, stmt, where);
+		Mem_row[] rslt_rows = (Mem_row[])tmp_where_rows.To_ary_and_clear(Mem_row.class);
+		if (qry2 != null) {
+			if (qry2.Order() != null && qry2.Order().Flds().length > 0)
+				Array_.Sort(rslt_rows, new Mem_sorter(qry2.Order().Flds()));
+			int offset = qry2.Offset();
+			if (offset != Db_qry__select_cmd.Offset__disabled) {
+				Mem_row[] trg_rows = new Mem_row[rslt_rows.length - offset];
+				Array_.Copy_to(rslt_rows, offset, trg_rows, 0, trg_rows.length);
+				rslt_rows = trg_rows;
+			}
+			int limit = qry2.Limit();
+			if (limit != Db_qry__select_cmd.Limit__disabled) {
+				Mem_row[] trg_rows = new Mem_row[limit];
+				Array_.Copy_to(rslt_rows, 0, trg_rows, 0, limit);
+				rslt_rows = trg_rows;
+			}
+			rslt_rows = Mem_exec_.Rows__select_flds(rslt_rows, qry2.Cols());
+		}
+		return new Mem_rdr(select, rslt_rows);
+	}
+}
+class Mem_sorter implements gplx.core.lists.ComparerAble {
+	private final    Sql_order_fld[] flds;
+	public Mem_sorter(Sql_order_fld[] flds) {
+		this.flds = flds;
+	}
+	public int compare(Object lhsObj, Object rhsObj) {
+		Mem_row lhs = (Mem_row)lhsObj;
+		Mem_row rhs = (Mem_row)rhsObj;
+		int flds_len = flds.length;
+		for (int i = 0; i < flds_len; ++i) {
+			Sql_order_fld fld = flds[i];
+			Object lhs_val = lhs.Get_by(fld.Name);
+			Object rhs_val = rhs.Get_by(fld.Name);
+			int comp = CompareAble_.Compare_obj(lhs_val, rhs_val);
+			if (comp != CompareAble_.Same) return comp * (fld.Sort == Sql_order_fld.Sort__dsc ? -1 : 1);
+		}
+		return CompareAble_.Same;
+	}
+}
+class Mem_exec_ {
+	public static Mem_row[] Rows__join(int join_tid, Mem_row[] lhs_rows, Mem_row[] rhs_rows, String tbl_alias, Sql_join_fld[] join_flds) {
+		int join_flds_len = join_flds.length;
+		Bry_bfr bfr = Bry_bfr_.New();
+		Hash_adp_bry rhs_hash = Hash_adp_bry.cs();
+		int rhs_rows_len = rhs_rows.length;
+		for (int i = 0; i < rhs_rows_len; ++i) {
+			Mem_row rhs_row = rhs_rows[i];
+			byte[] rhs_key = Rows__bld_key(bfr, Bool_.N, tbl_alias, rhs_row, join_flds, join_flds_len);
+			List_adp rhs_list = (List_adp)rhs_hash.Get_by_bry(rhs_key);
+			if (rhs_list == null) {
+				rhs_list = List_adp_.New();
+				rhs_hash.Add(rhs_key, rhs_list);
+			}
+			rhs_list.Add(rhs_row);
+		}
+		List_adp rv = List_adp_.New();
+		int lhs_len = lhs_rows.length;
+		for (int i = 0; i < lhs_len; ++i) {
+			Mem_row lhs_row = lhs_rows[i];
+			byte[] lhs_key = Rows__bld_key(bfr, Bool_.Y, tbl_alias, lhs_row, join_flds, join_flds_len);
+			List_adp rhs_list = (List_adp)rhs_hash.Get_by_bry(lhs_key);
+			if (rhs_list == null) {
+				switch (join_tid) {
+					case Sql_tbl_itm.Tid__inner: continue;
+					case Sql_tbl_itm.Tid__left: break;
+					default: throw Err_.new_unhandled_default(join_tid);
+				}
+			}
+			int rhs_list_len = rhs_list == null ? 1 : rhs_list.Len();
+			for (int j = 0; j < rhs_list_len; ++j) {
+				Mem_row rhs_row = rhs_list == null ? Mem_row.Null_row : (Mem_row)rhs_list.Get_at(j); 
+				Mem_row merged = Rows__merge(lhs_row, rhs_row);
+				rv.Add(merged);
+			}
+		}
+		return (Mem_row[])rv.To_ary_and_clear(Mem_row.class);
+	}
+	public static Mem_row[] Rows__alias(Mem_row[] src_rows, String tbl_alias) {
+		int src_rows_len = src_rows.length;
+		Mem_row[] rv = new Mem_row[src_rows_len];
+		for (int i = 0; i < src_rows_len; ++i) {
+			Mem_row src_row = src_rows[i];
+			Mem_row trg_row = new Mem_row(); rv[i] = trg_row;
+			int src_flds_len = src_row.Len();
+			for (int j = 0; j < src_flds_len; ++j) {
+				String fld = src_row.Fld_at(j);
+				Object val = src_row.Get_at(j);
+				trg_row.Add(Sql_select_fld.Bld_tbl_w_fld(tbl_alias, fld), val);
+			}
+		}
+		return rv;
+	}
+	private static byte[] Rows__bld_key(Bry_bfr bfr, boolean join_is_src, String trg_tbl, Mem_row row, Sql_join_fld[] join_flds, int join_flds_len) {
+		for (int i = 0; i < join_flds_len; ++i) {
+			if (i != 0) bfr.Add_byte_pipe();
+			Sql_join_fld join_fld = join_flds[i];
+			Object val = row.Get_by(join_fld.To_fld_sql(join_is_src, trg_tbl));
+			bfr.Add_obj(val);
+		}
+		return bfr.To_bry_and_clear();
+	}
+	private static Mem_row Rows__merge(Mem_row lhs, Mem_row rhs) {
+		Mem_row rv = new Mem_row();
+		Rows__copy_to(lhs, rv);
+		Rows__copy_to(rhs, rv);
+		return rv;
+	}
+	private static void Rows__copy_to(Mem_row src, Mem_row trg) {
+		int src_len = src.Len();
+		for (int i = 0; i < src_len; ++i) {
+			String fld = src.Fld_at(i);
+			Object val = src.Get_by_or_dbnull(fld);
+			trg.Add(fld, val);
+		}
+	}
+	public static Mem_row[] Rows__select_flds(Mem_row[] src_rows, Sql_select_clause cols) {
+		Sql_select_fld_list select_flds = cols.Flds; int select_flds_len = select_flds.Len();
+		int src_rows_len = src_rows.length;
+		Mem_row[] rv = new Mem_row[src_rows_len];
+		for (int i = 0; i < src_rows_len; ++i) {							// loop over each row
+			Mem_row src_row = src_rows[i];
+			Mem_row trg_row = new Mem_row(); rv[i] = trg_row;
+			for (int j = 0; j < select_flds_len; ++j) {						// loop over each fld
+				Sql_select_fld fld = select_flds.Get_at(j);
+				if (String_.Eq(fld.Alias, Sql_select_fld.Fld__wildcard)) {	// wildcard; add all cols
+					for (int k = 0; k < src_row.Len(); ++k) {
+						String key = src_row.Fld_at(k);
+						Object val = src_row.Get_by_or_dbnull(key);
+						trg_row.Add(key, val);
+					}
+				}
+				else {														// regular field; add it only
+					String key = fld.To_fld_key();
+					Object val = src_row.Get_by_or_dbnull(key);
+					trg_row.Add(fld.To_fld_alias(), val);
+				}
+			}
+		}
+		return rv;
+	}
+	public static String[] Flds__to_str_ary(Sql_select_fld_list flds) {
+		int len = flds.Len();
+		String[] rv = new String[len];
+		for (int i = 0; i < len; ++i)
+			rv[i] = flds.Get_at(i).Fld;
+		return rv;
+	}
+	public static void Where__filter(List_adp rv, Mem_row[] rows, Mem_stmt stmt, Criteria crt) {
+		rv.Clear();
+		int rows_len = rows.length;
+		for (int i = 0; i < rows_len; ++i) {
+			Mem_row itm = rows[i];
+			if (crt.Matches(itm)) 
+				rv.Add(itm);
+		}
+	}
+}

140_dbs/src/gplx/dbs/engines/mems/Mem_exec_select_tst.java

@@ -13,3 +13,116 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.engines.mems; import gplx.*; import gplx.dbs.*; import gplx.dbs.engines.*;
+import org.junit.*; import gplx.dbs.sqls.itms.*;
+public class Mem_exec_select_tst {
+	private final Mem_db_fxt__single fxt = new Mem_db_fxt__single();
+	@Test    public void Basic() {
+		fxt.Exec__create_tbl("tbl_1", "fld_1");
+		fxt.Exec__insert("tbl_1"
+		, String_.Ary("a_1")
+		, String_.Ary("a_2")
+		, String_.Ary("a_0")
+		);
+
+		// select all
+		fxt.Test__select(Db_qry_.select_().From_("tbl_1").Cols_all_()
+		, String_.Ary("a_1")
+		, String_.Ary("a_2")
+		, String_.Ary("a_0")
+		);
+
+		// order by
+		fxt.Test__select(Db_qry_.select_().From_("tbl_1").Cols_all_().Order_("fld_1", Bool_.N)
+		, String_.Ary("a_2")
+		, String_.Ary("a_1")
+		, String_.Ary("a_0")
+		);
+
+		// offset
+		fxt.Test__select(Db_qry_.select_().From_("tbl_1").Cols_all_().Offset_(1)
+		, String_.Ary("a_2")
+		, String_.Ary("a_0")
+		);
+
+		// limit
+		fxt.Test__select(Db_qry_.select_().From_("tbl_1").Cols_all_().Limit_(2)
+		, String_.Ary("a_1")
+		, String_.Ary("a_2")
+		);
+	}
+	@Test    public void Join__single() {
+		fxt.Exec__create_tbl("tbl_1", "fld_a", "fld_1a");
+		fxt.Exec__create_tbl("tbl_2", "fld_a", "fld_2a");
+		fxt.Exec__insert("tbl_1"
+		, String_.Ary("a_0", "1a_0")
+		, String_.Ary("a_1", "1a_1")
+		, String_.Ary("a_2", "1a_2")
+		);
+		fxt.Exec__insert("tbl_2"
+		, String_.Ary("a_0", "2a_0")
+		, String_.Ary("a_2", "2a_2")
+		);
+
+		// inner join
+		fxt.Test__select(Db_qry_.select_()
+		.Cols_w_tbl_("t1", "fld_a", "fld_1a").Cols_w_tbl_("t2", "fld_2a")
+		.From_("tbl_1", "t1")
+		.	Join_("tbl_2", "t2", Db_qry_.New_join__join("fld_a", "t1", "fld_a"))
+		, String_.Ary("a_0", "1a_0", "2a_0")
+		, String_.Ary("a_2", "1a_2", "2a_2")
+		);
+
+		// left join
+		fxt.Test__select(Db_qry_.select_()
+		.Cols_w_tbl_("t1", "fld_a", "fld_1a").Cols_w_tbl_("t2", "fld_2a")
+		.From_("tbl_1", "t1")
+		.	Join_(Sql_tbl_itm.Tid__left, Sql_tbl_itm.Db__null, "tbl_2", "t2", Db_qry_.New_join__join("fld_a", "t1", "fld_a"))
+		, String_.Ary("a_0", "1a_0", "2a_0")
+		, String_.Ary("a_1", "1a_1", Db_null.Null_str)
+		, String_.Ary("a_2", "1a_2", "2a_2")
+		);
+	}
+	@Test    public void Join__many() {
+		fxt.Exec__create_tbl("tbl_1", "fld_a", "fld_1a");
+		fxt.Exec__create_tbl("tbl_2", "fld_a", "fld_2a");
+		fxt.Exec__insert("tbl_1"
+		, String_.Ary("a_0", "1a_0")
+		, String_.Ary("a_1", "1a_1")
+		);
+		fxt.Exec__insert("tbl_2"
+		, String_.Ary("a_0", "2a_0")
+		, String_.Ary("a_0", "2a_1")
+		);
+
+		// inner join
+		fxt.Test__select(Db_qry_.select_()
+		.Cols_w_tbl_("t1", "fld_a", "fld_1a").Cols_w_tbl_("t2", "fld_2a")
+		.From_("tbl_1", "t1")
+		.	Join_("tbl_2", "t2", Db_qry_.New_join__join("fld_a", "t1", "fld_a"))
+		, String_.Ary("a_0", "1a_0", "2a_0")
+		, String_.Ary("a_0", "1a_0", "2a_1")
+		);
+
+		// left join
+		fxt.Test__select(Db_qry_.select_()
+		.Cols_w_tbl_("t1", "fld_a", "fld_1a").Cols_w_tbl_("t2", "fld_2a")
+		.From_("tbl_1", "t1")
+		.	Join_(Sql_tbl_itm.Tid__left, Sql_tbl_itm.Db__null, "tbl_2", "t2", Db_qry_.New_join__join("fld_a", "t1", "fld_a"))
+		, String_.Ary("a_0", "1a_0", "2a_0")
+		, String_.Ary("a_0", "1a_0", "2a_1")
+		, String_.Ary("a_1", "1a_1", Db_null.Null_str)
+		);
+	}
+}
+class Mem_db_fxt__single {
+	private final Mem_db_fxt mem_fxt;
+	private final Db_conn conn;
+	public Mem_db_fxt__single() {
+		this.mem_fxt = new Mem_db_fxt();
+		this.conn = mem_fxt.Make_conn("mem/test.db");
+	}
+	public void Exec__create_tbl	(String tbl, String... fld_names)		{mem_fxt.Exec__create_tbl(conn, tbl, fld_names);}
+	public void Exec__insert		(String tbl, String[]... rows)		{mem_fxt.Exec__insert(conn, tbl, rows);}
+	public void Test__select		(Db_qry qry, String[]... expd)		{mem_fxt.Test__select(conn, qry, expd);}
+}

140_dbs/src/gplx/dbs/engines/mems/Mem_qry_set.java

@@ -13,3 +13,10 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.engines.mems; import gplx.*; import gplx.dbs.*; import gplx.dbs.engines.*;
+public class Mem_qry_set {
+	private final    List_adp rows = List_adp_.New();
+	public int Len() {return rows.Count();}
+	public Mem_row Get_at(int i) {return (Mem_row)rows.Get_at(i);}
+	public void Add(Mem_row row) {rows.Add(row);}
+}

140_dbs/src/gplx/dbs/engines/mems/Mem_rdr.java

@@ -13,3 +13,32 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.engines.mems; import gplx.*; import gplx.dbs.*; import gplx.dbs.engines.*;
+public class Mem_rdr implements Db_rdr {
+	private final    Mem_row[] rows; private int row_idx = -1; private final    int rows_len;
+	private Mem_row row;
+	public Mem_rdr(String[] cols, Mem_row[] rows) {
+		this.rows = rows; this.rows_len = rows.length;
+	}
+	public boolean Move_next() {
+		boolean rv = ++row_idx < rows_len;
+		if (rv)
+			row = rows[row_idx];
+		return rv;
+	}
+	public byte[] Read_bry(String k)			{return (byte[])row.Get_by(k);}
+	public String Read_str(String k)			{return (String)row.Get_by(k);}
+	public byte[] Read_bry_by_str(String k)		{return Bry_.new_u8_safe((String)row.Get_by(k));}		// NOTE: null b/c db can have NULL
+	@gplx.Virtual public void Save_bry_in_parts(Io_url url, String tbl, String fld, String crt_key, Object crt_val) {throw Err_.new_unimplemented();}
+	public DateAdp Read_date_by_str(String k)	{return DateAdp_.parse_iso8561((String)row.Get_by(k));}
+	public byte Read_byte(String k)				{return Byte_.Cast(row.Get_by(k));}
+	public int Read_int(String k)				{return Int_.Cast(row.Get_by(k));}
+	public long Read_long(String k)				{return Long_.cast(row.Get_by(k));}
+	public float Read_float(String k)			{return Float_.cast(row.Get_by(k));}
+	public double Read_double(String k)			{return Double_.cast(row.Get_by(k));}
+	public boolean Read_bool_by_byte(String k)		{return Byte_.Cast(row.Get_by(k)) == 1;}
+	public int Fld_len()						{return row.Len();}
+	public Object Read_obj(String k)			{return row.Get_by(k);}
+	public Object Read_at(int i)				{return row.Get_at(i);}
+	public void Rls()							{}
+}

140_dbs/src/gplx/dbs/engines/mems/Mem_row.java

@@ -13,3 +13,25 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.engines.mems; import gplx.*; import gplx.dbs.*; import gplx.dbs.engines.*;
+public class Mem_row implements Gfo_invk {
+	private final    Ordered_hash hash = Ordered_hash_.New();
+	private final    Ordered_hash flds = Ordered_hash_.New();
+	public int		Len() {return hash.Len();}
+	public String	Fld_at(int i) {return (String)flds.Get_at(i);}
+	public Object	Get_at(int i) {return hash.Get_at(i);}
+	public Object	Get_by(String key) {return hash.Get_by(key);}
+	public Object	Get_by_or_dbnull(String key) {
+		Object rv = hash.Get_by(key);
+		return rv == null ? Db_null.Instance : rv;
+	}
+	public void		Set_by(String key, Object val)		{hash.Add_if_dupe_use_nth(key, val); flds.Add_if_dupe_use_1st(key, key);}
+	public void		Add(String key, Object val)			{hash.Add(key, val); flds.Add_if_dupe_use_1st(key, key);}
+	public Object Invk(GfsCtx ctx, int ikey, String k, GfoMsg m) {
+		Object rv = Get_by(k);
+		if (rv == null) return Gfo_invk_.Rv_unhandled;
+		return rv;
+	}
+	public static final    Mem_row[] Ary_empty = new Mem_row[0];
+        public static final    Mem_row Null_row = new Mem_row();
+}

140_dbs/src/gplx/dbs/engines/mems/Mem_stmt.java

@@ -13,3 +13,134 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.engines.mems; import gplx.*; import gplx.dbs.*; import gplx.dbs.engines.*;
+import gplx.core.stores.*;
+public class Mem_stmt implements Db_stmt {
+	private static final String Key_na = ""; // key is not_available; only called by procs with signature of Val(<type> v);
+	private final    Ordered_hash val_list = Ordered_hash_.New();
+	public Mem_stmt(Mem_engine engine, Db_qry qry) {Ctor_stmt(engine, qry);} private Mem_engine engine;
+	public void Ctor_stmt(Db_engine engine, Db_qry qry) {this.engine = (Mem_engine)engine; this.qry = qry;}
+	public Mem_stmt_args Stmt_args() {return stmt_args;} private final    Mem_stmt_args stmt_args = new Mem_stmt_args();
+	public int Args_len() {return val_list.Count();}
+	public Object Args_get_at(int i)	{return val_list.Get_at(i);}
+	public Object Args_get_by(String k) {return val_list.Get_by(k);}
+	public Db_qry Qry() {return qry;} private Db_qry qry;
+	public Db_stmt Reset_stmt() {return this;}
+	public Db_stmt Clear() {
+		val_list.Clear();
+		stmt_args.Clear();
+		return this;
+	}
+	public void Rls() {this.Clear();}
+	public Db_stmt Crt_bool_as_byte(String k, boolean v)	{return Add_byte_by_bool(Bool_.Y, k, v);}
+	public Db_stmt Val_bool_as_byte(String k, boolean v)	{return Add_byte_by_bool(Bool_.N, k, v);}
+	public Db_stmt Val_bool_as_byte(boolean v)				{return Add_byte_by_bool(Bool_.N, Key_na, v);}
+	private Db_stmt Add_byte_by_bool(boolean where, String k, boolean v) {return Add_byte(where, k, v ? Bool_.Y_byte : Bool_.N_byte);}
+	public Db_stmt Crt_byte(String k, byte v)	{return Add_byte(Bool_.Y, k, v);}
+	public Db_stmt Val_byte(String k, byte v)	{return Add_byte(Bool_.N, k, v);}
+	public Db_stmt Val_byte(byte v)				{return Add_byte(Bool_.N, Key_na, v);}
+	private Db_stmt Add_byte(boolean where, String k, byte v) {
+		try {Add(k, where, v);} catch (Exception e) {throw Err_.new_exc(e, "db", "failed to add value", "type", "byte", "val", v);}
+		return this;
+	}
+	public Db_stmt Crt_int(String k, int v)	{return Add_int(Bool_.Y, k, v);}
+	public Db_stmt Val_int_by_bool(String k, boolean v)	{return Add_int(Bool_.N, k, v ? 1 : 0);}
+	public Db_stmt Val_int(String k, int v)	{return Add_int(Bool_.N, k, v);}
+	public Db_stmt Val_int(int v)			{return Add_int(Bool_.N, Key_na, v);}
+	private Db_stmt Add_int(boolean where, String k, int v) {
+		try {Add(k, where, v);} catch (Exception e) {throw Err_.new_exc(e, "db", "failed to add value", "type", "int", "val", v);}
+		return this;
+	}
+	public Db_stmt Crt_long(String k, long v)	{return Add_long(Bool_.Y, k, v);}
+	public Db_stmt Val_long(String k, long v)	{return Add_long(Bool_.N, k, v);}
+	public Db_stmt Val_long(long v)				{return Add_long(Bool_.N, Key_na, v);}
+	private Db_stmt Add_long(boolean where, String k, long v) {
+		try {Add(k, where, v);} catch (Exception e) {throw Err_.new_exc(e, "db", "failed to add value", "type", "long", "val", v);} 
+		return this;
+	}
+	public Db_stmt Crt_float(String k, float v)	{return Add_float(Bool_.Y, k, v);}
+	public Db_stmt Val_float(String k, float v)	{return Add_float(Bool_.N, k, v);}
+	public Db_stmt Val_float(float v)			{return Add_float(Bool_.N, Key_na, v);}
+	private Db_stmt Add_float(boolean where, String k, float v) {
+		try {Add(k, where, v);} catch (Exception e) {throw Err_.new_exc(e, "db", "failed to add value", "type", "float", "val", v);}
+		return this;
+	}
+	public Db_stmt Crt_double(String k, double v)	{return Add_double(Bool_.Y, k, v);}
+	public Db_stmt Val_double(String k, double v)	{return Add_double(Bool_.N, k, v);}
+	public Db_stmt Val_double(double v)				{return Add_double(Bool_.N, Key_na, v);}
+	private Db_stmt Add_double(boolean where, String k, double v) {
+		try {Add(k, where, v);} catch (Exception e) {throw Err_.new_exc(e, "db", "failed to add value", "type", "double", "val", v);} 
+		return this;
+	}
+	public Db_stmt Crt_decimal(String k, Decimal_adp v)	{return Add_decimal(Bool_.Y, k, v);}
+	public Db_stmt Val_decimal(String k, Decimal_adp v)	{return Add_decimal(Bool_.N, k, v);}
+	public Db_stmt Val_decimal(Decimal_adp v)			{return Add_decimal(Bool_.N, Key_na, v);}
+	private Db_stmt Add_decimal(boolean where, String k, Decimal_adp v) {
+		try {Add(k, where, v);} catch (Exception e) {throw Err_.new_exc(e, "db", "failed to add value", "type", "decimal", "val", v);} 
+		return this;
+	}
+	public Db_stmt Crt_bry(String k, byte[] v)	{return Add_bry(Bool_.Y, k, v);}
+	public Db_stmt Val_bry(String k, byte[] v)	{return Add_bry(Bool_.N, k, v);}
+	public Db_stmt Val_bry(byte[] v)			{return Add_bry(Bool_.N, Key_na, v);}
+	private Db_stmt Add_bry(boolean where, String k, byte[] v) {
+		try {Add(k, where, v);} catch (Exception e) {throw Err_.new_exc(e, "db", "failed to add value", "type", "byte[]", "val", v.length);} 
+		return this;
+	}
+	public Db_stmt Crt_bry_as_str(String k, byte[] v)	{return Add_bry_as_str(Bool_.Y, k, v);}
+	public Db_stmt Val_bry_as_str(String k, byte[] v)	{return Add_bry_as_str(Bool_.N, k, v);}
+	public Db_stmt Val_bry_as_str(byte[] v)				{return Add_bry_as_str(Bool_.N, Key_na, v);}
+	private Db_stmt Add_bry_as_str(boolean where, String k, byte[] v) {return Add_str(where, k, String_.new_u8(v));}
+	public Db_stmt Crt_str(String k, String v)	{return Add_str(Bool_.Y, k, v);}
+	public Db_stmt Val_str(String k, String v)	{return Add_str(Bool_.N, k, v);}
+	public Db_stmt Val_str(String v)			{return Add_str(Bool_.N, Key_na, v);}
+	private Db_stmt Add_str(boolean where, String k, String v) {
+		try {Add(k, where, v);} catch (Exception e) {throw Err_.new_exc(e, "db", "failed to add value", "type", "String", "val", v);} 
+		return this;
+	}
+	public Db_stmt Crt_date(String k, DateAdp v)	{return Add_date(Bool_.Y, k, v);}
+	public Db_stmt Val_date(String k, DateAdp v)	{return Add_date(Bool_.N, k, v);}
+	private Db_stmt Add_date(boolean where, String k, DateAdp v) {
+		try {Add(k, where, v);} catch (Exception e) {throw Err_.new_exc(e, "db", "failed to add value", "type", "date", "val", v);} 
+		return this;
+	}
+	public Db_stmt Crt_text(String k, String v)		{return Add_text(Bool_.Y, k, v);}
+	public Db_stmt Val_text(String k, String v)		{return Add_text(Bool_.N, k, v);}
+	private Db_stmt Add_text(boolean where, String k, String v) {
+		try {Add(k, where, v);} catch (Exception e) {throw Err_.new_exc(e, "db", "failed to add value", "type", "text", "val", v);} 
+		return this;
+	}
+	public Db_stmt Val_rdr_(gplx.core.ios.streams.Io_stream_rdr v, long rdr_len) {
+		try {
+			Bry_bfr bfr = Bry_bfr_.New();
+			gplx.core.ios.streams.Io_stream_rdr_.Load_all_to_bfr(bfr, v);
+			Add("", Bool_.N, bfr.To_str_and_clear());
+		} catch (Exception e) {throw Err_.new_exc(e, "db", "failed to add value", "type", "rdr", "val", v);} 
+		return this;
+	}
+	public boolean Exec_insert() {
+		Mem_tbl tbl = engine.Tbls__get(qry.Base_table());
+		if (tbl == null) throw Err_.new_wo_type("must call Create_tbl", "tbl", qry.Base_table());
+		return tbl.Insert(this) == 1;
+	}
+	public int Exec_update() {
+		Mem_tbl tbl = engine.Tbls__get(qry.Base_table());
+		return tbl.Update(this);
+	}
+	public int Exec_delete() {
+		Mem_tbl tbl = engine.Tbls__get(qry.Base_table());
+		return tbl.Delete(this);
+	}
+	public DataRdr Exec_select() {throw Err_.new_unimplemented();}	
+	public Db_rdr Exec_select__rls_auto() {return this.Exec_select__rls_manual();}
+	public Db_rdr Exec_select__rls_manual() {
+//			Mem_tbl tbl = engine.Tbls_get(qry.Base_table());
+//			return tbl.Select(this);
+		return engine.Qry_runner().Select(this);
+	}
+	public Object Exec_select_val() {throw Err_.new_unimplemented();}
+	private void Add(String k, boolean where, Object v) {
+		if (k == Dbmeta_fld_itm.Key_null) return;		// key is explicitly null; ignore; allows schema_2+ type definitions
+		val_list.Add_if_dupe_use_1st(k, v);				// NOTE: only add if new; WHERE with IN will call Add many times; fld_ttl IN ('A.png', 'B.png');
+		if (where) stmt_args.Add(k, v);
+	}
+}

140_dbs/src/gplx/dbs/engines/mems/Mem_stmt_args.java

@@ -13,3 +13,63 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.engines.mems; import gplx.*; import gplx.dbs.*; import gplx.dbs.engines.*;
+import gplx.core.criterias.*;
+public class Mem_stmt_args {
+	private final    List_adp list = List_adp_.New();
+	private int cur_idx = -1;
+	public void Clear() {list.Clear(); cur_idx = -1;}
+	public void Add(String k, Object v) {list.Add(Keyval_.new_(k, v));}
+	public Keyval Get_next() {
+		int idx = ++cur_idx;
+		return idx == list.Count() ? null: (Keyval)list.Get_at(idx);
+	}
+}
+class Mem_stmt_args_ {
+	public static void Fill(Mem_stmt_args args, Criteria crt) {
+		int tid = crt.Tid();
+		if (tid == Criteria_.Tid_wrapper) {
+			Criteria_fld fld = (Criteria_fld)crt;
+			Criteria sub = fld.Crt();
+			String fld_key = fld.Key();
+			switch (sub.Tid()) {
+				case Criteria_.Tid_eq:
+				case Criteria_.Tid_comp:
+				case Criteria_.Tid_like:
+				case Criteria_.Tid_iomatch:
+					Keyval kvp = args.Get_next();
+					if (!String_.Eq(kvp.Key(), fld.Key())) throw Err_.new_("db", "fld_crt.key mismatch", "fld.key", fld_key, "kvp.key", kvp.Key());
+					sub.Val_as_obj_(kvp.Val());
+					break;
+				case Criteria_.Tid_in:
+					Criteria_in crt_in = (Criteria_in)sub;
+					Object[] ary = crt_in.Ary(); int ary_len = crt_in.Ary_len();
+					for (int i = 0; i < ary_len; ++i)
+						ary[i] = args.Get_next().Val();
+					break;
+				case Criteria_.Tid_between:
+					Criteria_between crt_between = (Criteria_between)sub;
+					crt_between.Lo_((Comparable)(args.Get_next()).Val());
+					crt_between.Hi_((Comparable)(args.Get_next()).Val());
+					break;
+				default: throw Err_.new_unhandled(sub.Tid());
+			}
+		}
+		else {
+			switch (tid) {
+				case Criteria_.Tid_const: break;	// true / false; nothing to fill
+				case Criteria_.Tid_and:
+				case Criteria_.Tid_or:
+					Criteria_bool_base crt_dual = (Criteria_bool_base)crt;
+					Fill(args, crt_dual.Lhs());
+					Fill(args, crt_dual.Rhs());
+					break;
+				case Criteria_.Tid_not:
+					Criteria_not crt_not = (Criteria_not)crt;
+					Fill(args, crt_not.Crt());
+					break;
+				default: throw Err_.new_unhandled(tid);
+			}
+		}
+	}
+}

140_dbs/src/gplx/dbs/engines/mems/Mem_tbl.java

@@ -13,3 +13,92 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.engines.mems; import gplx.*; import gplx.dbs.*; import gplx.dbs.engines.*;
+import gplx.core.primitives.*; import gplx.core.criterias.*; import gplx.dbs.qrys.*; import gplx.dbs.sqls.itms.*;
+import gplx.dbs.metas.*;
+public class Mem_tbl {
+	private final    List_adp where_rows = List_adp_.New();
+	private final    Hash_adp autonum_hash = Hash_adp_.New();		
+	public Mem_tbl(Dbmeta_tbl_itm meta) {this.meta = meta;}
+	public Dbmeta_tbl_itm Meta() {return meta;} private final    Dbmeta_tbl_itm meta;
+	public final    List_adp rows = List_adp_.New(); 
+	public int Insert(Mem_stmt stmt) {
+		Mem_row itm = new Mem_row();
+		Dbmeta_fld_mgr flds = meta.Flds();
+		int len = flds.Len();
+		for (int i = 0; i < len; ++i) {
+			Dbmeta_fld_itm fld = flds.Get_at(i);
+			String fld_name = fld.Name();
+			Object val = fld.Autonum() ? Autonum_calc(fld_name) : stmt.Args_get_by(fld_name);
+			if (val == null) continue; // NOTE: allow Bulk_insert from test to skip filds
+			itm.Set_by(fld_name, val);
+		}
+		rows.Add(itm);
+		return 1;
+	}
+	private int Autonum_calc(String name) {
+		Int_obj_ref autonum_itm = (Int_obj_ref)autonum_hash.Get_by(name);
+		if (autonum_itm == null) {
+			autonum_itm = Int_obj_ref.New(0);
+			autonum_hash.Add(name, autonum_itm);
+		}
+		return autonum_itm.Val_add();
+	}
+	public int Update(Mem_stmt stmt) {
+		Db_qry_update qry = (Db_qry_update)stmt.Qry();
+		Criteria where_crt = qry.Where(); if (where_crt == null) where_crt = Criteria_.All;
+		Mem_stmt_args_.Fill(stmt.Stmt_args(), where_crt);
+		Select_rows_where(where_rows, stmt, where_crt);
+		int where_rows_len = where_rows.Count();
+		String[] update_cols = qry.Cols_for_update(); int update_cols_len = update_cols.length;
+		for (int i = 0; i < where_rows_len; ++i) {
+			Mem_row itm = (Mem_row)where_rows.Get_at(i);
+			for (int j = 0; j < update_cols_len; ++j)
+				itm.Set_by(update_cols[j], stmt.Args_get_at(j));
+		}
+		return where_rows_len;
+	}
+	public int Delete(Mem_stmt stmt) {
+		Db_qry_delete qry = (Db_qry_delete)stmt.Qry();
+		Mem_stmt_args_.Fill(stmt.Stmt_args(), qry.Where());
+		Select_rows_where(where_rows, stmt, qry.Where());
+		int where_rows_len = where_rows.Count();
+		for (int i = 0; i < where_rows_len; ++i) {
+			Mem_row itm = (Mem_row)where_rows.Get_at(i);
+			rows.Del(itm);
+		}
+		return where_rows_len;
+	}
+	public Db_rdr Select(Mem_stmt stmt) {
+		String[] select = null; Criteria where = null;
+		Db_qry__select_in_tbl qry = Db_qry__select_in_tbl.as_(stmt.Qry());
+		if (qry == null) {
+			Db_qry__select_cmd qry2 = (Db_qry__select_cmd)stmt.Qry();
+			select = To_str_ary(qry2.Cols().Flds);
+			where = qry2.Where_itm().Root;
+		}
+		else {
+			select = qry.Select_flds();
+			where = qry.Where();
+		}
+		Mem_stmt_args_.Fill(stmt.Stmt_args(), where);
+		Select_rows_where(where_rows, stmt, where);
+		return new Mem_rdr(select, (Mem_row[])where_rows.To_ary_and_clear(Mem_row.class));
+	}
+	private String[] To_str_ary(Sql_select_fld_list flds) {
+		int len = flds.Len();
+		String[] rv = new String[len];
+		for (int i = 0; i < len; ++i)
+			rv[i] = flds.Get_at(i).Fld;
+		return rv;
+	}
+	private void Select_rows_where(List_adp rv, Mem_stmt stmt, Criteria crt) {
+		rv.Clear();
+		int rows_len = rows.Count();
+		for (int i = 0; i < rows_len; ++i) {
+			Mem_row itm = (Mem_row)rows.Get_at(i);
+			if (crt.Matches(itm)) 
+				rv.Add(itm);
+		}
+	}
+}

140_dbs/src/gplx/dbs/engines/mysql/Mysql_conn_info.java

@@ -13,3 +13,31 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.engines.mysql; import gplx.*; import gplx.dbs.*; import gplx.dbs.engines.*;
+public class Mysql_conn_info extends Db_conn_info__base {
+	public Mysql_conn_info(String raw, String db_api, String database, String server, String uid, String pwd) {super(raw, db_api, database);
+		this.server = server;
+		this.uid = uid;
+		this.pwd = pwd;
+	}
+	@Override public String Key() {return Tid_const;} public static final String Tid_const = "mysql";
+	public String Server() {return server;} private final String server;
+	public String Uid() {return uid;} private final String uid;
+	public String Pwd() {return pwd;} private final String pwd;
+	public static Db_conn_info new_(String server, String database, String uid, String pwd) {
+		return Db_conn_info_.parse(Bld_raw
+		( "gplx_key", Tid_const
+		, "server", server
+		, "database", database
+		, "uid", uid
+		, "pwd", pwd
+		, "charset", "utf8"
+		));
+	}
+	@Override public Db_conn_info New_self(String raw, Keyval_hash hash) {
+		return new Mysql_conn_info
+			( raw, Bld_api(hash, Keyval_.new_("charset", "utf8")), hash.Get_val_as_str_or_fail("database")
+			, hash.Get_val_as_str_or_fail("server"), hash.Get_val_as_str_or_fail("uid"), hash.Get_val_as_str_or_fail("pwd"));
+	}
+        public static final Mysql_conn_info Instance = new Mysql_conn_info("", "", "", "", "", "");
+}

140_dbs/src/gplx/dbs/engines/mysql/Mysql_engine.java

@@ -13,3 +13,36 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.engines.mysql; import gplx.*; import gplx.dbs.*; import gplx.dbs.engines.*;
+import gplx.core.stores.*; import gplx.dbs.engines.*; import gplx.dbs.sqls.*; import gplx.dbs.metas.*;
+import java.sql.*; 
+public class Mysql_engine extends Db_engine_sql_base {
+	@Override public String Tid() {return Mysql_conn_info.Tid_const;}
+	@Override public Sql_qry_wtr	Sql_wtr() {return Sql_qry_wtr_.New__mysql();}
+	@Override public Db_engine New_clone(Db_conn_info connectInfo) {
+		Mysql_engine rv = new Mysql_engine();
+		rv.Ctor(connectInfo);
+		return rv;
+	}
+	@Override public DataRdr New_rdr(ResultSet rdr, String commandText) {return Mysql_rdr.new_(rdr, commandText);}
+	@Override public Dbmeta_tbl_mgr Meta_mgr() {throw Err_.new_unimplemented();}
+		@gplx.Internal @Override protected Connection Conn_make() {
+		Mysql_conn_info conn_info_as_mysql = (Mysql_conn_info)conn_info; 
+		Connection rv = Conn_make_by_url("jdbc:mysql://localhost/" + conn_info_as_mysql.Database() + "?characterEncoding=UTF8&useSSL=false", conn_info_as_mysql.Uid(), conn_info_as_mysql.Pwd());
+		return rv;
+	}
+		public static final    Mysql_engine Instance = new Mysql_engine(); Mysql_engine() {}
+}
+class Mysql_rdr extends Db_data_rdr {
+		//PATCH:MYSQL:byte actually returned as int by Jdbc ResultSet (or MYSQL impmentation); convert to byte 
+	@Override public byte ReadByte(String key) {return ReadByteOr(key, Byte.MAX_VALUE);}
+	@Override public byte ReadByteOr(String key, byte or) {
+		Object val = Read(key);
+		return val == null ? or : ((Integer)val).byteValue();
+	}
+	public static Mysql_rdr new_(ResultSet rdr, String commandText) {
+		Mysql_rdr rv = new Mysql_rdr();
+		rv.ctor_db_data_rdr(rdr, commandText);
+		return rv;
+	}	Mysql_rdr() {}
+}

140_dbs/src/gplx/dbs/engines/noops/Noop_conn_info.java

@@ -13,3 +13,10 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.engines.noops; import gplx.*; import gplx.dbs.*; import gplx.dbs.engines.*;
+public class Noop_conn_info extends Db_conn_info__base {
+	public Noop_conn_info(String raw, String db_api, String database) {super(raw, db_api, database);}
+	@Override public String Key() {return Tid_const;} public static final    String Tid_const = "null_db";
+	@Override public Db_conn_info New_self(String raw, Keyval_hash hash) {return this;}
+	public static final    Noop_conn_info Instance = new Noop_conn_info("gplx_key=null_db", "", "");
+}

140_dbs/src/gplx/dbs/engines/noops/Noop_engine.java

@@ -13,3 +13,38 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+ package gplx.dbs.engines.noops; import gplx.*; import gplx.dbs.*; import gplx.dbs.engines.*;
+import gplx.core.stores.*; import gplx.dbs.metas.*; import gplx.dbs.sqls.*; import gplx.dbs.conn_props.*; import gplx.dbs.qrys.bats.*;
+public class Noop_engine implements Db_engine {
+	public String				Tid() {return Noop_conn_info.Tid_const;}
+	public Db_conn_info			Conn_info() {return Db_conn_info_.Null;}
+	public Db_conn_props_mgr	Props() {return props;} private final    Db_conn_props_mgr props = new Db_conn_props_mgr();
+	public Db_batch_mgr			Batch_mgr() {return batch_mgr;} private final    Db_batch_mgr batch_mgr = new Db_batch_mgr();
+	public Sql_qry_wtr			Sql_wtr() {return sql_wtr;} private final    Sql_qry_wtr sql_wtr = Sql_qry_wtr_.New__basic();
+	public void					Conn_open() {}
+	public void					Conn_term() {}
+	public Db_engine			New_clone(Db_conn_info url) {return this;}
+	public Db_rdr				Exec_as_rdr__rls_manual	(Object rdr_obj, String sql)				{return Db_rdr_.Empty;}
+	public Db_rdr				Exec_as_rdr__rls_auto	(Db_stmt stmt, Object rdr_obj, String sql)	{return Db_rdr_.Empty;}
+	public Db_stmt				Stmt_by_qry(Db_qry qry) {return Db_stmt_.Null;}
+	public Object				Stmt_by_sql(String sql) {throw Err_.new_unimplemented();}
+	public DataRdr				New_rdr(java.sql.ResultSet rdr, String sql) {return DataRdr_.Null;} 
+	public void					Txn_bgn(String name)	{}
+	public String				Txn_end()				{return "";}
+	public void					Txn_cxl()				{}
+	public void					Txn_sav()				{}
+	public Object				Exec_as_obj(Db_qry cmd) {return cmd.Exec_is_rdr() ? (Object)DataRdr_.Null : -1;}
+	public void					Meta_tbl_create(Dbmeta_tbl_itm meta) {}
+	public void					Meta_tbl_delete(String tbl)						{}
+	public void					Meta_idx_create(Gfo_usr_dlg usr_dlg, Dbmeta_idx_itm... ary) {}
+	public void					Meta_idx_delete(String idx) {}
+	public void					Meta_fld_append(String tbl, Dbmeta_fld_itm fld)	{}
+	public void					Env_db_attach(String alias, Db_conn conn)		{}
+	public void					Env_db_attach(String alias, Io_url db_url)		{}
+	public void					Env_db_detach(String alias)						{}
+	public boolean					Meta_tbl_exists(String tbl)						{return false;}
+	public boolean					Meta_fld_exists(String tbl, String fld)			{return false;}
+	public boolean					Meta_idx_exists(String idx)						{return false;}
+	public Dbmeta_tbl_mgr		Meta_mgr()										{return meta_tbl_mgr;} private final    Dbmeta_tbl_mgr meta_tbl_mgr = new Dbmeta_tbl_mgr(Dbmeta_reload_cmd_.Noop);
+        public static final    Noop_engine Instance = new Noop_engine(); Noop_engine() {}
+}

140_dbs/src/gplx/dbs/engines/postgres/Postgres_conn_info.java

@@ -13,3 +13,32 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.engines.postgres; import gplx.*; import gplx.dbs.*; import gplx.dbs.engines.*;
+public class Postgres_conn_info extends Db_conn_info__base {
+	public Postgres_conn_info(String raw, String db_api, String database, String server, String uid, String pwd) {super(raw, db_api, database);
+		this.server = server;
+		this.uid = uid;
+		this.pwd = pwd;
+	}
+	@Override public String Key() {return Tid_const;} public static final String Tid_const = "postgresql";
+	public String Server() {return server;} private final String server;
+	public String Uid() {return uid;} private final String uid;
+	public String Pwd() {return pwd;} private final String pwd;
+	public static Db_conn_info new_(String server, String database, String uid, String pwd) {
+		return Db_conn_info_.parse(Bld_raw
+		( "gplx_key", Tid_const
+		, "server", server
+		, "database", database
+		, "port", "5432"
+		, "user id", uid
+		, "password", pwd
+		, "encoding", "unicode"	// needed for 1.1 conn; otherwise, ascii
+		));
+	}
+	@Override public Db_conn_info New_self(String raw, Keyval_hash hash) {
+		return new Postgres_conn_info
+			( raw, Bld_api(hash, Keyval_.new_("encoding", "unicode")), hash.Get_val_as_str_or_fail("database")
+			, hash.Get_val_as_str_or_fail("server"), hash.Get_val_as_str_or_fail("user id"), hash.Get_val_as_str_or_fail("password"));
+	}
+        public static final Postgres_conn_info Instance = new Postgres_conn_info("", "", "", "", "", "");
+}

140_dbs/src/gplx/dbs/engines/postgres/Postgres_engine.java

@@ -13,3 +13,22 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.engines.postgres; import gplx.*; import gplx.dbs.*; import gplx.dbs.engines.*;
+import gplx.core.stores.*; import gplx.dbs.engines.*; import gplx.dbs.sqls.*; import gplx.dbs.metas.*;
+import java.sql.*; 
+public class Postgres_engine extends Db_engine_sql_base {
+	@Override public String Tid() {return Postgres_conn_info.Tid_const;}
+	@Override public Sql_qry_wtr	Sql_wtr() {return Sql_qry_wtr_.New__mysql();}
+	@Override public Db_engine New_clone(Db_conn_info connectInfo) {
+		Postgres_engine rv = new Postgres_engine();
+		rv.Ctor(connectInfo);
+		return rv;
+	}
+	@Override public DataRdr New_rdr(ResultSet rdr, String commandText) {return Db_data_rdr_.new_(rdr, commandText);}
+	@Override public Dbmeta_tbl_mgr Meta_mgr() {throw Err_.new_unimplemented();}
+		@gplx.Internal @Override protected Connection Conn_make() {
+		Postgres_conn_info conn_info_as_postgres = (Postgres_conn_info)conn_info;
+		return Conn_make_by_url("jdbc:" + conn_info_as_postgres.Key() + "://localhost/" + conn_info_as_postgres.Database(), conn_info_as_postgres.Uid(), conn_info_as_postgres.Pwd());
+	}
+		public static final    Postgres_engine Instance = new Postgres_engine(); Postgres_engine() {}
+}

140_dbs/src/gplx/dbs/engines/sqlite/Sqlite_conn_info.java

@@ -13,3 +13,35 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.engines.sqlite; import gplx.*; import gplx.dbs.*; import gplx.dbs.engines.*;
+public class Sqlite_conn_info extends Db_conn_info__base {
+	public Sqlite_conn_info(String raw, String db_api, String database, Io_url url) {super(raw, db_api, database);this.url = url;}
+	@Override public String Key() {return Key_const;} public static final String Key_const = "sqlite";
+	public Io_url Url() {return url;} private final Io_url url;
+	@Override public Db_conn_info New_self(String raw, Keyval_hash hash) {
+		Io_url url = Io_url_.new_any_(hash.Get_val_as_str_or_fail("data source"));
+		String db = url.NameOnly();
+		String api = Bld_api(hash, Keyval_.new_("version", "3"));
+		return new Sqlite_conn_info(raw, api, db, url);
+	}
+
+	public static final Sqlite_conn_info Instance = new Sqlite_conn_info("", "", "", Io_url_.Empty);
+	public static Db_conn_info load_(Io_url url) {
+		return Db_conn_info_.parse(Bld_raw
+		( "gplx_key"		, Key_const
+		, Cs__data_source	, url.Xto_api()
+		, Cs__version		, Cs__version__3
+		));
+	}
+	public static Db_conn_info make_(Io_url url) {
+		Io_mgr.Instance.CreateDirIfAbsent(url.OwnerDir());
+		return Db_conn_info_.parse(Bld_raw
+		( "gplx_key"		, Key_const
+		, Cs__data_source	, url.Xto_api()
+		, Cs__version		, Cs__version__3
+			
+		));
+	}
+	public static final String Cs__data_source = "data source", Cs__version = "version", Cs__version__3 = "3";
+	public static Io_url To_url(Db_conn conn) {return ((Sqlite_conn_info)conn.Conn_info()).url;}
+}

140_dbs/src/gplx/dbs/engines/sqlite/Sqlite_engine.java

@@ -13,3 +13,151 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.engines.sqlite; import gplx.*; import gplx.dbs.*; import gplx.dbs.engines.*;
+import java.sql.*; 
+import gplx.core.stores.*; import gplx.dbs.engines.*; import gplx.dbs.engines.sqlite.*; import gplx.dbs.metas.*; import gplx.dbs.sqls.*;
+import gplx.dbs.qrys.*; 
+import gplx.core.ios.IoItmFil;
+import org.sqlite.SQLiteConnection;
+public class Sqlite_engine extends Db_engine_sql_base {
+	private final    Sqlite_txn_mgr txn_mgr; private final    Sqlite_schema_mgr schema_mgr;
+	Sqlite_engine() {
+		this.txn_mgr = new Sqlite_txn_mgr(this);
+		this.schema_mgr = new Sqlite_schema_mgr(this);
+	}
+	@Override public String Tid() {return Sqlite_conn_info.Key_const;}
+	@Override public gplx.dbs.sqls.Sql_qry_wtr Sql_wtr() {return Sql_qry_wtr_.New__sqlite();}
+	@Override public Db_engine New_clone(Db_conn_info connectInfo) {
+		Sqlite_engine rv = new Sqlite_engine();
+		rv.Ctor(connectInfo);
+		return rv;
+	}
+	@Override public DataRdr New_rdr(ResultSet rdr, String commandText) {return Sqlite_rdr.new_(rdr, commandText);}
+	@Override public Db_rdr	New_rdr_clone() {return new Db_rdr__sqlite();}
+	@Override public void	Env_db_attach(String alias, Db_conn conn)	{
+		Db_conn_info cs_obj = conn.Conn_info(); if (!String_.Eq(cs_obj.Key(), Sqlite_conn_info.Key_const)) throw Err_.new_("dbs", "must attach to sqlite databases", "conn", cs_obj.Raw());
+		Sqlite_conn_info cs = (Sqlite_conn_info)cs_obj;
+		Env_db_attach(alias, cs.Url());
+	}
+	@Override public void			Env_db_attach(String alias, Io_url db_url)	{Exec_as_int(String_.Format("ATTACH '{0}' AS {1};", db_url.Raw(), alias));}
+	@Override public void			Env_db_detach(String alias)					{Exec_as_int(String_.Format("DETACH {0};", alias));}
+	@Override public void			Txn_bgn(String name)						{txn_mgr.Txn_bgn(name);}
+	@Override public String			Txn_end()									{return txn_mgr.Txn_end();}
+	@Override public void			Txn_cxl()									{txn_mgr.Txn_cxl();}
+	@Override public void			Txn_sav()									{txn_mgr.Txn_sav();}
+	@Override public Dbmeta_tbl_mgr	Meta_mgr()									{return schema_mgr.Tbl_mgr();}
+	@Override public boolean			Meta_tbl_exists(String tbl)					{return schema_mgr.Tbl_exists(tbl);}
+	@Override public boolean			Meta_fld_exists(String tbl, String fld)		{return schema_mgr.Fld_exists(tbl, fld);}
+	@Override public boolean			Meta_idx_exists(String idx)					{return schema_mgr.Idx_exists(idx);}
+	@Override public Db_stmt Stmt_by_qry(Db_qry qry) {return new Sqlite_stmt(this, qry);}
+		private static boolean loaded = false;
+	protected void Meta_tbl_gather_hook() {throw Err_.new_unimplemented();}
+	@gplx.Internal @Override protected Connection Conn_make() {
+		if (!loaded) {
+			try {
+				Class.forName("org.sqlite.JDBC");
+			}
+			catch (ClassNotFoundException e) {throw Err_.new_exc(e, "db", "could not load sqlite jdbc driver");}
+			loaded = true;					
+		}
+		
+		// init vars for opening connection
+		Sqlite_conn_info conn_info_as_sqlite = (Sqlite_conn_info)conn_info;
+		Io_url sqlite_fs_url = conn_info_as_sqlite.Url();
+		String sqlite_db_url = "jdbc:sqlite://" + String_.Replace(sqlite_fs_url.Raw(), "\\", "/");
+		
+		// set open_mode flag if conn is read-only; needed else all SELECT queries will be very slow; DATE:2016-09-03
+		IoItmFil sqlite_fs_itm = Io_mgr.Instance.QueryFil(sqlite_fs_url);
+		Keyval[] props = sqlite_fs_itm.Exists() && sqlite_fs_itm.ReadOnly()	// NOTE: must check if it exists; else missing-file will be marked as readonly connection, and missing-file will sometimes be dynamically created as read-write; DATE:2016-09-04
+			? Keyval_.Ary(Keyval_.new_("open_mode", "1"))
+			: Keyval_.Ary_empty;
+
+		// open connection
+		Connection rv = Conn__new_by_url_and_props(sqlite_db_url, props);
+		
+		// set busyTimeout; needed else multiple processes accessing same db can cause "database is locked" error; DATE:2016-09-03
+		SQLiteConnection rv_as_sqlite = (org.sqlite.SQLiteConnection)rv;
+		try {rv_as_sqlite.setBusyTimeout(10000);}
+		catch (SQLException e) {Gfo_usr_dlg_.Instance.Warn_many("", "", "failed to set busy timeout; err=~{0}", Err_.Message_gplx_log(e));}
+		return rv;
+	}
+		public static final    Sqlite_engine Instance = new Sqlite_engine();
+}
+class Db_rdr__sqlite extends Db_rdr__basic {	@Override public byte Read_byte(String k)		{try {return (byte)Int_.Cast(rdr.getObject(k));} catch (Exception e) {throw Err_.new_exc(e, "db", "read failed", "k", k, "type", Byte_.Cls_val_name);}} 
+		@Override public boolean Read_bool_by_byte(String k) {
+		try {
+			int val = rdr.getInt(k);
+			return val == 1;
+		} 	catch (Exception e) {throw Err_.new_exc(e, "db", "read failed", "i", k, "type", Bool_.Cls_val_name);}
+	}
+	@Override public long Read_long(String k) {
+		try {
+			long val = rdr.getLong(k);
+			Number n = (Number)val;
+			return n.longValue();
+		} 	catch (Exception e) {throw Err_.new_exc(e, "db", "read failed", "i", k, "type", Long_.Cls_val_name);}
+	}
+	@Override public float Read_float(String k) {
+		try {
+			Double val = (Double)rdr.getDouble(k);
+			return val == null ? Float.NaN : val.floatValue();
+		} 	catch (Exception e) {throw Err_.new_exc(e, "db", "read failed:", "i", k, "type", Float_.Cls_val_name);}
+	}
+	@Override public DateAdp Read_date_by_str(String k) {
+		try {
+			String val = rdr.getString(k);
+			return val == null ? null : DateAdp_.parse_fmt(val, "yyyyMMdd_HHmmss");
+		} 	catch (Exception e) {throw Err_.new_exc(e, "db", "read failed", "i", k, "type", DateAdp_.Cls_ref_type);}
+	}
+//	@Override public DecimalAdp ReadDecimalOr(String key, DecimalAdp or) {
+//		Object val = Read(key);
+//		Double d = ((Double)val);
+//		return val == null ? null : DecimalAdp_.double_(d);
+//	}
+	}
+class Sqlite_rdr extends Db_data_rdr {		@Override public float ReadFloat(String key) {return ReadFloatOr(key, Float.NaN);}
+	@Override public float ReadFloatOr(String key, float or) {
+		Object val = Read(key);
+		Double d = ((Double)val);
+		return val == null ? or : d.floatValue();
+	}
+	@Override public Decimal_adp ReadDecimal(String key) {return ReadDecimalOr(key, null);}
+	@Override public Decimal_adp ReadDecimalOr(String key, Decimal_adp or) {
+		Object val = Read(key);
+		Double d = ((Double)val);
+		return val == null ? or : Decimal_adp_.double_(d);
+	}
+	@Override public DateAdp ReadDate(String key) {return ReadDateOr(key, null);}
+	@Override public DateAdp ReadDateOr(String key, DateAdp or) {
+		Object val = Read(key);
+		return val == null ? or : DateAdp_.parse_fmt((String)val, "M/dd/yyyy hh:mm tt");
+	}
+	@Override public boolean ReadBool(String key) {return ReadBoolOr(key, false);}
+	@Override public boolean ReadBoolOr(String key, boolean or) {
+		Object val = Read(key);
+		return val == null ? or : Int_.Cast(val) == 1;
+	}
+	@Override public byte ReadByte(String key) {return ReadByteOr(key, Byte_.Zero);}
+	@Override public byte ReadByteOr(String key, byte or) {
+		Object val = Read(key);
+		return val == null ? or : (byte)Int_.Cast(val);
+	}
+	@Override public long ReadLong(String key) {return ReadLongOr(key, Long_.Min_value);}
+	@Override public long ReadLongOr(String key, long or) {
+		Object val = Read(key);
+		if (val == null) return or;
+		Number n = (Number)val;
+		return n.longValue();
+	}
+		public static Sqlite_rdr new_(ResultSet rdr, String commandText) {
+		Sqlite_rdr rv = new Sqlite_rdr();
+		rv.ctor_db_data_rdr(rdr, commandText);
+		return rv;
+	}	Sqlite_rdr() {}
+}
+class Sqlite_stmt extends gplx.dbs.qrys.Db_stmt_cmd {	public Sqlite_stmt(Db_engine engine, Db_qry qry) {super(engine, qry);}
+	@Override protected Db_stmt Add_date(boolean where, String k, DateAdp v) {
+		if (k == Dbmeta_fld_itm.Key_null) return this;	// key is explicitly null; ignore; allows version_2+ type definitions
+		return super.Add_str(where, k, v.XtoStr_fmt_iso_8561());
+	}
+}

140_dbs/src/gplx/dbs/engines/sqlite/Sqlite_engine_.java

@@ -13,3 +13,65 @@ The terms of each license can be found in the source code repository:
 GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
 Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
 */
+package gplx.dbs.engines.sqlite; import gplx.*; import gplx.dbs.*; import gplx.dbs.engines.*;
+import gplx.core.primitives.*;	import gplx.dbs.qrys.*; import gplx.dbs.utls.*; import gplx.dbs.engines.*; import gplx.dbs.engines.sqlite.*;
+public class Sqlite_engine_ {
+	public static void Db_attach(Db_conn p, String alias, String url) {
+		String s = String_.Format("ATTACH '{0}' AS {1};", url, alias);
+		Db_qry qry = Db_qry_sql.xtn_(s);
+		p.Exec_qry(qry);
+	}
+	public static void Db_detach(Db_conn p, String alias) {
+		String s = String_.Format("DETACH '{0}';", alias);
+		Db_qry qry = Db_qry_sql.xtn_(s);
+		p.Exec_qry(qry);
+	}
+	public static void Tbl_create_and_delete(Db_conn p, String tbl_name, String tbl_sql) {
+		Tbl_delete(p, tbl_name);
+		Db_qry qry = Db_qry_sql.ddl_(tbl_sql);
+		p.Exec_qry(qry);
+	}
+	public static void Tbl_create(Db_conn p, String tbl_name, String tbl_sql) {
+		Db_qry qry = Db_qry_sql.ddl_(tbl_sql);
+		p.Exec_qry(qry);
+	}
+	public static void Tbl_delete_many(Db_conn p, String... tbls) {
+		int len = tbls.length;
+		for (int i = 0; i < len; i++)
+			Tbl_delete(p, tbls[i]);
+	}
+	public static void Tbl_delete(Db_conn p, String tbl) {
+		Db_qry qry = Db_qry_sql.ddl_("DROP TABLE IF EXISTS " + tbl + ";");
+		p.Exec_qry(qry);
+	}
+	public static void Tbl_rename(Db_conn p, String src, String trg) {
+		Db_qry qry = Db_qry_sql.ddl_(String_.Format("ALTER TABLE {0} RENAME TO {1};", src, trg));
+		p.Exec_qry(qry);
+	}
+	public static void Idx_create(Gfo_usr_dlg usr_dlg, Db_conn conn, String tbl, Dbmeta_idx_itm[] idx_ary) {
+		int len = idx_ary.length;
+		for (int i = 0; i < len; ++i) {
+			Dbmeta_idx_itm idx = idx_ary[i];
+			String idx_sql = idx.To_sql_create(conn.Engine().Sql_wtr());
+			usr_dlg.Plog_many("", "", "creating index: ~{0} ~{1}", tbl, idx_sql);
+			conn.Exec_qry(Db_qry_sql.ddl_(idx.To_sql_create(conn.Engine().Sql_wtr())));
+			usr_dlg.Log_many("", "", "index created: ~{0} ~{1}", tbl, idx_sql);
+		}
+	}
+	public static void Idx_create(Db_conn p, Db_idx_itm... idxs) {Idx_create(Gfo_usr_dlg_.Noop, p, "", idxs);}
+	public static void Idx_create(Gfo_usr_dlg usr_dlg, Db_conn p, String file_id, Db_idx_itm... idxs) {
+		int len = idxs.length;
+		for (int i = 0; i < len; i++) {
+			String index = idxs[i].Xto_sql();
+			usr_dlg.Plog_many("", "", "creating index: ~{0} ~{1}", file_id, index);
+			p.Exec_qry(Db_qry_sql.ddl_(index));
+			usr_dlg.Log_many("", "", "index created: ~{0} ~{1}", file_id, index);
+		}
+	}
+	public static final int Stmt_arg_max = 999;					// 999 is max number of variables allowed by sqlite
+	public static final boolean Supports_read_binary_stream = false;	
+	public static final boolean Supports_indexed_by = true;			
+	public static String X_date_to_str(DateAdp v) {return v == Date_null ? "" : v.XtoStr_fmt_iso_8561();}
+	public static final    DateAdp Date_null = null;
+	public static final byte Wildcard_byte = Byte_ascii.Hash;
+}