/*
** 2001 September 15
**
** The author disclaims copyright to this source code. In place of
** a legal notice, here is a blessing:
**
** May you do good and not evil.
** May you find forgiveness for yourself and forgive others.
** May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** in order to generate code for DELETE FROM statements.
*/
#include "sqliteInt.h"

/*
** While a SrcList can in general represent multiple tables and subqueries
** (as in the FROM clause of a SELECT statement) in this case it contains
** the name of a single table, as one might find in an INSERT, DELETE,
** or UPDATE statement. Look up that table in the symbol table and
** return a pointer. Set an error message and return NULL if the table
** name is not found or if any other error occurs.
**
** The following fields are initialized appropriate in pSrc:
**
** pSrc->a[0].spTab Pointer to the Table object
** pSrc->a[0].u2.pIBIndex Pointer to the INDEXED BY index, if there is one
**
*/
Table *sqlite3SrcListLookup(Parse *pParse, SrcList *pSrc){
 SrcItem *pItem = pSrc->a;
 Table *pTab;
 assert( pItem && pSrc->nSrc>=1 );
 pTab = sqlite3LocateTableItem(pParse, 0, pItem);
 if( pItem->pSTab ) sqlite3DeleteTable(pParse->db, pItem->pSTab);
 pItem->pSTab = pTab;
 pItem->fg.notCte = 1;
 if( pTab ){
 pTab->nTabRef++;
 if( pItem->fg.isIndexedBy && sqlite3IndexedByLookup(pParse, pItem) ){
 pTab = 0;
 }
 }
 return pTab;
}

/* Generate byte-code that will report the number of rows modified
** by a DELETE, INSERT, or UPDATE statement.
*/
void sqlite3CodeChangeCount(Vdbe *v, int regCounter, const char *zColName){
 sqlite3VdbeAddOp0(v, OP_FkCheck);
 sqlite3VdbeAddOp2(v, OP_ResultRow, regCounter, 1);
 sqlite3VdbeSetNumCols(v, 1);
 sqlite3VdbeSetColName(v, 0, COLNAME_NAME, zColName, SQLITE_STATIC);
}

/* Return true if table pTab is read-only.
**
** A table is read-only if any of the following are true:
**
** 1) It is a virtual table and no implementation of the xUpdate method
** has been provided
**
** 2) A trigger is currently being coded and the table is a virtual table
** that is SQLITE_VTAB_DIRECTONLY or if PRAGMA trusted_schema=OFF and
** the table is not SQLITE_VTAB_INNOCUOUS.
**
** 3) It is a system table (i.e. sqlite_schema), this call is not
** part of a nested parse and writable_schema pragma has not
** been specified
**
** 4) The table is a shadow table, the database connection is in
** defensive mode, and the current sqlite3_prepare()
** is for a top-level SQL statement.
*/
static int vtabIsReadOnly(Parse *pParse, Table *pTab){
 assert( IsVirtual(pTab) );
 if( sqlite3GetVTable(pParse->db, pTab)->pMod->pModule->xUpdate==0 ){
 return 1;
 }

 /* Within triggers:
 ** * Do not allow DELETE, INSERT, or UPDATE of SQLITE_VTAB_DIRECTONLY
 ** virtual tables
 ** * Only allow DELETE, INSERT, or UPDATE of non-SQLITE_VTAB_INNOCUOUS
 ** virtual tables if PRAGMA trusted_schema=ON.
 */
 if( (pParse->pToplevel!=0 || (pParse->prepFlags & SQLITE_PREPARE_FROM_DDL))
 && pTab->u.vtab.p->eVtabRisk >
 ((pParse->db->flags & SQLITE_TrustedSchema)!=0)
 ){
 sqlite3ErrorMsg(pParse, "unsafe use of virtual table \"%s\"",
 pTab->zName);
 }
 return 0;
}
static int tabIsReadOnly(Parse *pParse, Table *pTab){
 sqlite3 *db;
 if( IsVirtual(pTab) ){
 return vtabIsReadOnly(pParse, pTab);
 }
 if( (pTab->tabFlags & (TF_Readonly|TF_Shadow))==0 ) return 0;
 db = pParse->db;
 if( (pTab->tabFlags & TF_Readonly)!=0 ){
 return sqlite3WritableSchema(db)==0 && pParse->nested==0;
 }
 assert( pTab->tabFlags & TF_Shadow );
 return sqlite3ReadOnlyShadowTables(db);
}

/*
** Check to make sure the given table is writable.
**
** If pTab is not writable -> generate an error message and return 1.
** If pTab is writable but other errors have occurred -> return 1.
** If pTab is writable and no prior errors -> return 0;
*/
int sqlite3IsReadOnly(Parse *pParse, Table *pTab, Trigger *pTrigger){
 if( tabIsReadOnly(pParse, pTab) ){
 sqlite3ErrorMsg(pParse, "table %s may not be modified", pTab->zName);
 return 1;
 }
#ifndef SQLITE_OMIT_VIEW
 if( IsView(pTab)
 && (pTrigger==0 || (pTrigger->bReturning && pTrigger->pNext==0))
 ){
 sqlite3ErrorMsg(pParse,"cannot modify %s because it is a view",pTab->zName);
 return 1;
 }
#endif
 return 0;
}


#if !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER)
/*
** Evaluate a view and store its result in an ephemeral table. The
** pWhere argument is an optional WHERE clause that restricts the
** set of rows in the view that are to be added to the ephemeral table.
*/
void sqlite3MaterializeView(
 Parse *pParse, /* Parsing context */
 Table *pView, /* View definition */
 Expr *pWhere, /* Optional WHERE clause to be added */
 ExprList *pOrderBy, /* Optional ORDER BY clause */
 Expr *pLimit, /* Optional LIMIT clause */
 int iCur /* Cursor number for ephemeral table */
){
 SelectDest dest;
 Select *pSel;
 SrcList *pFrom;
 sqlite3 *db = pParse->db;
 int iDb = sqlite3SchemaToIndex(db, pView->pSchema);
 pWhere = sqlite3ExprDup(db, pWhere, 0);
 pFrom = sqlite3SrcListAppend(pParse, 0, 0, 0);
 if( pFrom ){
 assert( pFrom->nSrc==1 );
 pFrom->a[0].zName = sqlite3DbStrDup(db, pView->zName);
 assert( pFrom->a[0].fg.fixedSchema==0 && pFrom->a[0].fg.isSubquery==0 );
 pFrom->a[0].u4.zDatabase = sqlite3DbStrDup(db, db->aDb[iDb].zDbSName);
 assert( pFrom->a[0].fg.isUsing==0 );
 assert( pFrom->a[0].u3.pOn==0 );
 }
 pSel = sqlite3SelectNew(pParse, 0, pFrom, pWhere, 0, 0, pOrderBy,
 SF_IncludeHidden, pLimit);
 sqlite3SelectDestInit(&dest, SRT_EphemTab, iCur);
 sqlite3Select(pParse, pSel, &dest);
 sqlite3SelectDelete(db, pSel);
}
#endif /* !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER) */

#if defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) && !defined(SQLITE_OMIT_SUBQUERY)
/*
** Generate an expression tree to implement the WHERE, ORDER BY,
** and LIMIT/OFFSET portion of DELETE and UPDATE statements.
**
** DELETE FROM table_wxyz WHERE a<5 ORDER BY a LIMIT 1;
** \__________________________/
** pLimitWhere (pInClause)
*/
Expr *sqlite3LimitWhere(
 Parse *pParse, /* The parser context */
 SrcList *pSrc, /* the FROM clause -- which tables to scan */
 Expr *pWhere, /* The WHERE clause. May be null */
 ExprList *pOrderBy, /* The ORDER BY clause. May be null */
 Expr *pLimit, /* The LIMIT clause. May be null */
 char *zStmtType /* Either DELETE or UPDATE. For err msgs. */
){
 sqlite3 *db = pParse->db;
 Expr *pLhs = NULL; /* LHS of IN(SELECT...) operator */
 Expr *pInClause = NULL; /* WHERE rowid IN ( select ) */
 ExprList *pEList = NULL; /* Expression list containing only pSelectRowid*/
 SrcList *pSelectSrc = NULL; /* SELECT rowid FROM x ... (dup of pSrc) */
 Select *pSelect = NULL; /* Complete SELECT tree */
 Table *pTab;

 /* Check that there isn't an ORDER BY without a LIMIT clause.
 */
 if( pOrderBy && pLimit==0 ) {
 sqlite3ErrorMsg(pParse, "ORDER BY without LIMIT on %s", zStmtType);
 sqlite3ExprDelete(pParse->db, pWhere);
 sqlite3ExprListDelete(pParse->db, pOrderBy);
 return 0;
 }

 /* We only need to generate a select expression if there
 ** is a limit/offset term to enforce.
 */
 if( pLimit == 0 ) {
 return pWhere;
 }

 /* Generate a select expression tree to enforce the limit/offset
 ** term for the DELETE or UPDATE statement. For example:
 ** DELETE FROM table_a WHERE col1=1 ORDER BY col2 LIMIT 1 OFFSET 1
 ** becomes:
 ** DELETE FROM table_a WHERE rowid IN (
 ** SELECT rowid FROM table_a WHERE col1=1 ORDER BY col2 LIMIT 1 OFFSET 1
 ** );
 */

 pTab = pSrc->a[0].pSTab;
 if( HasRowid(pTab) ){
 pLhs = sqlite3PExpr(pParse, TK_ROW, 0, 0);
 pEList = sqlite3ExprListAppend(
 pParse, 0, sqlite3PExpr(pParse, TK_ROW, 0, 0)
 );
 }else{
 Index *pPk = sqlite3PrimaryKeyIndex(pTab);
 assert( pPk!=0 );
 assert( pPk->nKeyCol>=1 );
 if( pPk->nKeyCol==1 ){
 const char *zName;
 assert( pPk->aiColumn[0]>=0 && pPk->aiColumn[0]<pTab->nCol );
 zName = pTab->aCol[pPk->aiColumn[0]].zCnName;
 pLhs = sqlite3Expr(db, TK_ID, zName);
 pEList = sqlite3ExprListAppend(pParse, 0, sqlite3Expr(db, TK_ID, zName));
 }else{
 int i;
 for(i=0; i<pPk->nKeyCol; i++){
 Expr *p;
 assert( pPk->aiColumn[i]>=0 && pPk->aiColumn[i]<pTab->nCol );
 p = sqlite3Expr(db, TK_ID, pTab->aCol[pPk->aiColumn[i]].zCnName);
 pEList = sqlite3ExprListAppend(pParse, pEList, p);
 }
 pLhs = sqlite3PExpr(pParse, TK_VECTOR, 0, 0);
 if( pLhs ){
 pLhs->x.pList = sqlite3ExprListDup(db, pEList, 0);
 }
 }
 }

 /* duplicate the FROM clause as it is needed by both the DELETE/UPDATE tree
 ** and the SELECT subtree. */
 pSrc->a[0].pSTab = 0;
 pSelectSrc = sqlite3SrcListDup(db, pSrc, 0);
 pSrc->a[0].pSTab = pTab;
 if( pSrc->a[0].fg.isIndexedBy ){
 assert( pSrc->a[0].fg.isCte==0 );
 pSrc->a[0].u2.pIBIndex = 0;
 pSrc->a[0].fg.isIndexedBy = 0;
 sqlite3DbFree(db, pSrc->a[0].u1.zIndexedBy);
 }else if( pSrc->a[0].fg.isCte ){
 pSrc->a[0].u2.pCteUse->nUse++;
 }

 /* generate the SELECT expression tree. */
 pSelect = sqlite3SelectNew(pParse, pEList, pSelectSrc, pWhere, 0 ,0,
 pOrderBy,0,pLimit
 );

 /* now generate the new WHERE rowid IN clause for the DELETE/UPDATE */
 pInClause = sqlite3PExpr(pParse, TK_IN, pLhs, 0);
 sqlite3PExprAddSelect(pParse, pInClause, pSelect);
 return pInClause;
}
#endif /* defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) */
 /* && !defined(SQLITE_OMIT_SUBQUERY) */

/*
** Generate code for a DELETE FROM statement.
**
** DELETE FROM table_wxyz WHERE a<5 AND b NOT NULL;
** \________/ \________________/
** pTabList pWhere
*/
void sqlite3DeleteFrom(
 Parse *pParse, /* The parser context */
 SrcList *pTabList, /* The table from which we should delete things */
 Expr *pWhere, /* The WHERE clause. May be null */
 ExprList *pOrderBy, /* ORDER BY clause. May be null */
 Expr *pLimit /* LIMIT clause. May be null */
){
 Vdbe *v; /* The virtual database engine */
 Table *pTab; /* The table from which records will be deleted */
 int i; /* Loop counter */
 WhereInfo *pWInfo; /* Information about the WHERE clause */
 Index *pIdx; /* For looping over indices of the table */
 int iTabCur; /* Cursor number for the table */
 int iDataCur = 0; /* VDBE cursor for the canonical data source */
 int iIdxCur = 0; /* Cursor number of the first index */
 int nIdx; /* Number of indices */
 sqlite3 *db; /* Main database structure */
 AuthContext sContext; /* Authorization context */
 NameContext sNC; /* Name context to resolve expressions in */
 int iDb; /* Database number */
 int memCnt = 0; /* Memory cell used for change counting */
 int rcauth; /* Value returned by authorization callback */
 int eOnePass; /* ONEPASS_OFF or _SINGLE or _MULTI */
 int aiCurOnePass[2]; /* The write cursors opened by WHERE_ONEPASS */
 u8 *aToOpen = 0; /* Open cursor iTabCur+j if aToOpen[j] is true */
 Index *pPk; /* The PRIMARY KEY index on the table */
 int iPk = 0; /* First of nPk registers holding PRIMARY KEY value */
 i16 nPk = 1; /* Number of columns in the PRIMARY KEY */
 int iKey; /* Memory cell holding key of row to be deleted */
 i16 nKey; /* Number of memory cells in the row key */
 int iEphCur = 0; /* Ephemeral table holding all primary key values */
 int iRowSet = 0; /* Register for rowset of rows to delete */
 int addrBypass = 0; /* Address of jump over the delete logic */
 int addrLoop = 0; /* Top of the delete loop */
 int addrEphOpen = 0; /* Instruction to open the Ephemeral table */
 int bComplex; /* True if there are triggers or FKs or
 ** subqueries in the WHERE clause */

#ifndef SQLITE_OMIT_TRIGGER
 int isView; /* True if attempting to delete from a view */
 Trigger *pTrigger; /* List of table triggers, if required */
#endif

 memset(&sContext, 0, sizeof(sContext));
 db = pParse->db;
 assert( db->pParse==pParse );
 if( pParse->nErr ){
 goto delete_from_cleanup;
 }
 assert( db->mallocFailed==0 );
 assert( pTabList->nSrc==1 );

 /* Locate the table which we want to delete. This table has to be
 ** put in an SrcList structure because some of the subroutines we
 ** will be calling are designed to work with multiple tables and expect
 ** an SrcList* parameter instead of just a Table* parameter.
 */
 pTab = sqlite3SrcListLookup(pParse, pTabList);
 if( pTab==0 ) goto delete_from_cleanup;

 /* Figure out if we have any triggers and if the table being
 ** deleted from is a view
 */
#ifndef SQLITE_OMIT_TRIGGER
 pTrigger = sqlite3TriggersExist(pParse, pTab, TK_DELETE, 0, 0);
 isView = IsView(pTab);
#else
# define pTrigger 0
# define isView 0
#endif
 bComplex = pTrigger || sqlite3FkRequired(pParse, pTab, 0, 0);
#ifdef SQLITE_OMIT_VIEW
# undef isView
# define isView 0
#endif

#if TREETRACE_ENABLED
 if( sqlite3TreeTrace & 0x10000 ){
 sqlite3TreeViewLine(0, "In sqlite3Delete() at %s:%d", __FILE__, __LINE__);
 sqlite3TreeViewDelete(pParse->pWith, pTabList, pWhere,
 pOrderBy, pLimit, pTrigger);
 }
#endif

#ifdef SQLITE_ENABLE_UPDATE_DELETE_LIMIT
 if( !isView ){
 pWhere = sqlite3LimitWhere(
 pParse, pTabList, pWhere, pOrderBy, pLimit, "DELETE"
 );
 pOrderBy = 0;
 pLimit = 0;
 }
#endif

 /* If pTab is really a view, make sure it has been initialized.
 */
 if( sqlite3ViewGetColumnNames(pParse, pTab) ){
 goto delete_from_cleanup;
 }

 if( sqlite3IsReadOnly(pParse, pTab, pTrigger) ){
 goto delete_from_cleanup;
 }
 iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
 assert( iDb<db->nDb );
 rcauth = sqlite3AuthCheck(pParse, SQLITE_DELETE, pTab->zName, 0,
 db->aDb[iDb].zDbSName);
 assert( rcauth==SQLITE_OK || rcauth==SQLITE_DENY || rcauth==SQLITE_IGNORE );
 if( rcauth==SQLITE_DENY ){
 goto delete_from_cleanup;
 }
 assert(!isView || pTrigger);

 /* Assign cursor numbers to the table and all its indices.
 */
 assert( pTabList->nSrc==1 );
 iTabCur = pTabList->a[0].iCursor = pParse->nTab++;
 for(nIdx=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, nIdx++){
 pParse->nTab++;
 }

 /* Start the view context
 */
 if( isView ){
 sqlite3AuthContextPush(pParse, &sContext, pTab->zName);
 }

 /* Begin generating code.
 */
 v = sqlite3GetVdbe(pParse);
 if( v==0 ){
 goto delete_from_cleanup;
 }
 if( pParse->nested==0 ) sqlite3VdbeCountChanges(v);
 sqlite3BeginWriteOperation(pParse, bComplex, iDb);

 /* If we are trying to delete from a view, realize that view into
 ** an ephemeral table.
 */
#if !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER)
 if( isView ){
 sqlite3MaterializeView(pParse, pTab,
 pWhere, pOrderBy, pLimit, iTabCur
 );
 iDataCur = iIdxCur = iTabCur;
 pOrderBy = 0;
 pLimit = 0;
 }
#endif

 /* Resolve the column names in the WHERE clause.
 */
 memset(&sNC, 0, sizeof(sNC));
 sNC.pParse = pParse;
 sNC.pSrcList = pTabList;
 if( sqlite3ResolveExprNames(&sNC, pWhere) ){
 goto delete_from_cleanup;
 }

 /* Initialize the counter of the number of rows deleted, if
 ** we are counting rows.
 */
 if( (db->flags & SQLITE_CountRows)!=0
 && !pParse->nested
 && !pParse->pTriggerTab
 && !pParse->bReturning
 ){
 memCnt = ++pParse->nMem;
 sqlite3VdbeAddOp2(v, OP_Integer, 0, memCnt);
 }

#ifndef SQLITE_OMIT_TRUNCATE_OPTIMIZATION
 /* Special case: A DELETE without a WHERE clause deletes everything.
 ** It is easier just to erase the whole table. Prior to version 3.6.5,
 ** this optimization caused the row change count (the value returned by
 ** API function sqlite3_count_changes) to be set incorrectly.
 **
 ** The "rcauth==SQLITE_OK" terms is the
 ** IMPLEMENTATION-OF: R-17228-37124 If the action code is SQLITE_DELETE and
 ** the callback returns SQLITE_IGNORE then the DELETE operation proceeds but
 ** the truncate optimization is disabled and all rows are deleted
 ** individually.
 */
 if( rcauth==SQLITE_OK
 && pWhere==0
 && !bComplex
 && !IsVirtual(pTab)
#ifdef SQLITE_ENABLE_PREUPDATE_HOOK
 && db->xPreUpdateCallback==0
#endif
 ){
 assert( !isView );
 sqlite3TableLock(pParse, iDb, pTab->tnum, 1, pTab->zName);
 if( HasRowid(pTab) ){
 sqlite3VdbeAddOp4(v, OP_Clear, pTab->tnum, iDb, memCnt ? memCnt : -1,
 pTab->zName, P4_STATIC);
 }
 for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
 assert( pIdx->pSchema==pTab->pSchema );
 if( IsPrimaryKeyIndex(pIdx) && !HasRowid(pTab) ){
 sqlite3VdbeAddOp3(v, OP_Clear, pIdx->tnum, iDb, memCnt ? memCnt : -1);
 }else{
 sqlite3VdbeAddOp2(v, OP_Clear, pIdx->tnum, iDb);
 }
 }
 }else
#endif /* SQLITE_OMIT_TRUNCATE_OPTIMIZATION */
 {
 u16 wcf = WHERE_ONEPASS_DESIRED|WHERE_DUPLICATES_OK;
 if( sNC.ncFlags & NC_Subquery ) bComplex = 1;
 wcf |= (bComplex ? 0 : WHERE_ONEPASS_MULTIROW);
 if( HasRowid(pTab) ){
 /* For a rowid table, initialize the RowSet to an empty set */
 pPk = 0;
 assert( nPk==1 );
 iRowSet = ++pParse->nMem;
 sqlite3VdbeAddOp2(v, OP_Null, 0, iRowSet);
 }else{
 /* For a WITHOUT ROWID table, create an ephemeral table used to
 ** hold all primary keys for rows to be deleted. */
 pPk = sqlite3PrimaryKeyIndex(pTab);
 assert( pPk!=0 );
 nPk = pPk->nKeyCol;
 iPk = pParse->nMem+1;
 pParse->nMem += nPk;
 iEphCur = pParse->nTab++;
 addrEphOpen = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, iEphCur, nPk);
 sqlite3VdbeSetP4KeyInfo(pParse, pPk);
 }
 
 /* Construct a query to find the rowid or primary key for every row
 ** to be deleted, based on the WHERE clause. Set variable eOnePass
 ** to indicate the strategy used to implement this delete:
 **
 ** ONEPASS_OFF: Two-pass approach - use a FIFO for rowids/PK values.
 ** ONEPASS_SINGLE: One-pass approach - at most one row deleted.
 ** ONEPASS_MULTI: One-pass approach - any number of rows may be deleted.
 */
 pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 0, 0,0,wcf,iTabCur+1);
 if( pWInfo==0 ) goto delete_from_cleanup;
 eOnePass = sqlite3WhereOkOnePass(pWInfo, aiCurOnePass);
 assert( IsVirtual(pTab)==0 || eOnePass!=ONEPASS_MULTI );
 assert( IsVirtual(pTab) || bComplex || eOnePass!=ONEPASS_OFF
 || OptimizationDisabled(db, SQLITE_OnePass) );
 if( eOnePass!=ONEPASS_SINGLE ) sqlite3MultiWrite(pParse);
 if( sqlite3WhereUsesDeferredSeek(pWInfo) ){
 sqlite3VdbeAddOp1(v, OP_FinishSeek, iTabCur);
 }
 
 /* Keep track of the number of rows to be deleted */
 if( memCnt ){
 sqlite3VdbeAddOp2(v, OP_AddImm, memCnt, 1);
 }
 
 /* Extract the rowid or primary key for the current row */
 if( pPk ){
 for(i=0; i<nPk; i++){
 assert( pPk->aiColumn[i]>=0 );
 sqlite3ExprCodeGetColumnOfTable(v, pTab, iTabCur,
 pPk->aiColumn[i], iPk+i);
 }
 iKey = iPk;
 }else{
 iKey = ++pParse->nMem;
 sqlite3ExprCodeGetColumnOfTable(v, pTab, iTabCur, -1, iKey);
 }
 
 if( eOnePass!=ONEPASS_OFF ){
 /* For ONEPASS, no need to store the rowid/primary-key. There is only
 ** one, so just keep it in its register(s) and fall through to the
 ** delete code. */
 nKey = nPk; /* OP_Found will use an unpacked key */
 aToOpen = sqlite3DbMallocRawNN(db, nIdx+2);
 if( aToOpen==0 ){
 sqlite3WhereEnd(pWInfo);
 goto delete_from_cleanup;
 }
 memset(aToOpen, 1, nIdx+1);
 aToOpen[nIdx+1] = 0;
 if( aiCurOnePass[0]>=0 ) aToOpen[aiCurOnePass[0]-iTabCur] = 0;
 if( aiCurOnePass[1]>=0 ) aToOpen[aiCurOnePass[1]-iTabCur] = 0;
 if( addrEphOpen ) sqlite3VdbeChangeToNoop(v, addrEphOpen);
 addrBypass = sqlite3VdbeMakeLabel(pParse);
 }else{
 if( pPk ){
 /* Add the PK key for this row to the temporary table */
 iKey = ++pParse->nMem;
 nKey = 0; /* Zero tells OP_Found to use a composite key */
 sqlite3VdbeAddOp4(v, OP_MakeRecord, iPk, nPk, iKey,
 sqlite3IndexAffinityStr(pParse->db, pPk), nPk);
 sqlite3VdbeAddOp4Int(v, OP_IdxInsert, iEphCur, iKey, iPk, nPk);
 }else{
 /* Add the rowid of the row to be deleted to the RowSet */
 nKey = 1; /* OP_DeferredSeek always uses a single rowid */
 sqlite3VdbeAddOp2(v, OP_RowSetAdd, iRowSet, iKey);
 }
 sqlite3WhereEnd(pWInfo);
 }
 
 /* Unless this is a view, open cursors for the table we are
 ** deleting from and all its indices. If this is a view, then the
 ** only effect this statement has is to fire the INSTEAD OF
 ** triggers.
 */
 if( !isView ){
 int iAddrOnce = 0;
 if( eOnePass==ONEPASS_MULTI ){
 iAddrOnce = sqlite3VdbeAddOp0(v, OP_Once); VdbeCoverage(v);
 }
 testcase( IsVirtual(pTab) );
 sqlite3OpenTableAndIndices(pParse, pTab, OP_OpenWrite, OPFLAG_FORDELETE,
 iTabCur, aToOpen, &iDataCur, &iIdxCur);
 assert( pPk || IsVirtual(pTab) || iDataCur==iTabCur );
 assert( pPk || IsVirtual(pTab) || iIdxCur==iDataCur+1 );
 if( eOnePass==ONEPASS_MULTI ){
 sqlite3VdbeJumpHereOrPopInst(v, iAddrOnce);
 }
 }
 
 /* Set up a loop over the rowids/primary-keys that were found in the
 ** where-clause loop above.
 */
 if( eOnePass!=ONEPASS_OFF ){
 assert( nKey==nPk ); /* OP_Found will use an unpacked key */
 if( !IsVirtual(pTab) && aToOpen[iDataCur-iTabCur] ){
 assert( pPk!=0 || IsView(pTab) );
 sqlite3VdbeAddOp4Int(v, OP_NotFound, iDataCur, addrBypass, iKey, nKey);
 VdbeCoverage(v);
 }
 }else if( pPk ){
 addrLoop = sqlite3VdbeAddOp1(v, OP_Rewind, iEphCur); VdbeCoverage(v);
 if( IsVirtual(pTab) ){
 sqlite3VdbeAddOp3(v, OP_Column, iEphCur, 0, iKey);
 }else{
 sqlite3VdbeAddOp2(v, OP_RowData, iEphCur, iKey);
 }
 assert( nKey==0 ); /* OP_Found will use a composite key */
 }else{
 addrLoop = sqlite3VdbeAddOp3(v, OP_RowSetRead, iRowSet, 0, iKey);
 VdbeCoverage(v);
 assert( nKey==1 );
 } 
 
 /* Delete the row */
#ifndef SQLITE_OMIT_VIRTUALTABLE
 if( IsVirtual(pTab) ){
 const char *pVTab = (const char *)sqlite3GetVTable(db, pTab);
 sqlite3VtabMakeWritable(pParse, pTab);
 assert( eOnePass==ONEPASS_OFF || eOnePass==ONEPASS_SINGLE );
 sqlite3MayAbort(pParse);
 if( eOnePass==ONEPASS_SINGLE ){
 sqlite3VdbeAddOp1(v, OP_Close, iTabCur);
 if( sqlite3IsToplevel(pParse) ){
 pParse->isMultiWrite = 0;
 }
 }
 sqlite3VdbeAddOp4(v, OP_VUpdate, 0, 1, iKey, pVTab, P4_VTAB);
 sqlite3VdbeChangeP5(v, OE_Abort);
 }else
#endif
 {
 int count = (pParse->nested==0); /* True to count changes */
 sqlite3GenerateRowDelete(pParse, pTab, pTrigger, iDataCur, iIdxCur,
 iKey, nKey, count, OE_Default, eOnePass, aiCurOnePass[1]);
 }
 
 /* End of the loop over all rowids/primary-keys. */
 if( eOnePass!=ONEPASS_OFF ){
 sqlite3VdbeResolveLabel(v, addrBypass);
 sqlite3WhereEnd(pWInfo);
 }else if( pPk ){
 sqlite3VdbeAddOp2(v, OP_Next, iEphCur, addrLoop+1); VdbeCoverage(v);
 sqlite3VdbeJumpHere(v, addrLoop);
 }else{
 sqlite3VdbeGoto(v, addrLoop);
 sqlite3VdbeJumpHere(v, addrLoop);
 } 
 } /* End non-truncate path */

 /* Update the sqlite_sequence table by storing the content of the
 ** maximum rowid counter values recorded while inserting into
 ** autoincrement tables.
 */
 if( pParse->nested==0 && pParse->pTriggerTab==0 ){
 sqlite3AutoincrementEnd(pParse);
 }

 /* Return the number of rows that were deleted. If this routine is
 ** generating code because of a call to sqlite3NestedParse(), do not
 ** invoke the callback function.
 */
 if( memCnt ){
 sqlite3CodeChangeCount(v, memCnt, "rows deleted");
 }

delete_from_cleanup:
 sqlite3AuthContextPop(&sContext);
 sqlite3SrcListDelete(db, pTabList);
 sqlite3ExprDelete(db, pWhere);
#if defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT)
 sqlite3ExprListDelete(db, pOrderBy);
 sqlite3ExprDelete(db, pLimit);
#endif
 if( aToOpen ) sqlite3DbNNFreeNN(db, aToOpen);
 return;
}
/* Make sure "isView" and other macros defined above are undefined. Otherwise
** they may interfere with compilation of other functions in this file
** (or in another file, if this file becomes part of the amalgamation). */
#ifdef isView
 #undef isView
#endif
#ifdef pTrigger
 #undef pTrigger
#endif

/*
** This routine generates VDBE code that causes a single row of a
** single table to be deleted. Both the original table entry and
** all indices are removed.
**
** Preconditions:
**
** 1. iDataCur is an open cursor on the btree that is the canonical data
** store for the table. (This will be either the table itself,
** in the case of a rowid table, or the PRIMARY KEY index in the case
** of a WITHOUT ROWID table.)
**
** 2. Read/write cursors for all indices of pTab must be open as
** cursor number iIdxCur+i for the i-th index.
**
** 3. The primary key for the row to be deleted must be stored in a
** sequence of nPk memory cells starting at iPk. If nPk==0 that means
** that a search record formed from OP_MakeRecord is contained in the
** single memory location iPk.
**
** eMode:
** Parameter eMode may be passed either ONEPASS_OFF (0), ONEPASS_SINGLE, or
** ONEPASS_MULTI. If eMode is not ONEPASS_OFF, then the cursor
** iDataCur already points to the row to delete. If eMode is ONEPASS_OFF
** then this function must seek iDataCur to the entry identified by iPk
** and nPk before reading from it.
**
** If eMode is ONEPASS_MULTI, then this call is being made as part
** of a ONEPASS delete that affects multiple rows. In this case, if
** iIdxNoSeek is a valid cursor number (>=0) and is not the same as
** iDataCur, then its position should be preserved following the delete
** operation. Or, if iIdxNoSeek is not a valid cursor number, the
** position of iDataCur should be preserved instead.
**
** iIdxNoSeek:
** If iIdxNoSeek is a valid cursor number (>=0) not equal to iDataCur,
** then it identifies an index cursor (from within array of cursors
** starting at iIdxCur) that already points to the index entry to be deleted.
** Except, this optimization is disabled if there are BEFORE triggers since
** the trigger body might have moved the cursor.
*/
void sqlite3GenerateRowDelete(
 Parse *pParse, /* Parsing context */
 Table *pTab, /* Table containing the row to be deleted */
 Trigger *pTrigger, /* List of triggers to (potentially) fire */
 int iDataCur, /* Cursor from which column data is extracted */
 int iIdxCur, /* First index cursor */
 int iPk, /* First memory cell containing the PRIMARY KEY */
 i16 nPk, /* Number of PRIMARY KEY memory cells */
 u8 count, /* If non-zero, increment the row change counter */
 u8 onconf, /* Default ON CONFLICT policy for triggers */
 u8 eMode, /* ONEPASS_OFF, _SINGLE, or _MULTI. See above */
 int iIdxNoSeek /* Cursor number of cursor that does not need seeking */
){
 Vdbe *v = pParse->pVdbe; /* Vdbe */
 int iOld = 0; /* First register in OLD.* array */
 int iLabel; /* Label resolved to end of generated code */
 u8 opSeek; /* Seek opcode */

 /* Vdbe is guaranteed to have been allocated by this stage. */
 assert( v );
 VdbeModuleComment((v, "BEGIN: GenRowDel(%d,%d,%d,%d)",
 iDataCur, iIdxCur, iPk, (int)nPk));

 /* Seek cursor iCur to the row to delete. If this row no longer exists
 ** (this can happen if a trigger program has already deleted it), do
 ** not attempt to delete it or fire any DELETE triggers. */
 iLabel = sqlite3VdbeMakeLabel(pParse);
 opSeek = HasRowid(pTab) ? OP_NotExists : OP_NotFound;
 if( eMode==ONEPASS_OFF ){
 sqlite3VdbeAddOp4Int(v, opSeek, iDataCur, iLabel, iPk, nPk);
 VdbeCoverageIf(v, opSeek==OP_NotExists);
 VdbeCoverageIf(v, opSeek==OP_NotFound);
 }

 /* If there are any triggers to fire, allocate a range of registers to
 ** use for the old.* references in the triggers. */
 if( sqlite3FkRequired(pParse, pTab, 0, 0) || pTrigger ){
 u32 mask; /* Mask of OLD.* columns in use */
 int iCol; /* Iterator used while populating OLD.* */
 int addrStart; /* Start of BEFORE trigger programs */

 /* TODO: Could use temporary registers here. Also could attempt to
 ** avoid copying the contents of the rowid register. */
 mask = sqlite3TriggerColmask(
 pParse, pTrigger, 0, 0, TRIGGER_BEFORE|TRIGGER_AFTER, pTab, onconf
 );
 mask |= sqlite3FkOldmask(pParse, pTab);
 iOld = pParse->nMem+1;
 pParse->nMem += (1 + pTab->nCol);

 /* Populate the OLD.* pseudo-table register array. These values will be
 ** used by any BEFORE and AFTER triggers that exist. */
 sqlite3VdbeAddOp2(v, OP_Copy, iPk, iOld);
 for(iCol=0; iCol<pTab->nCol; iCol++){
 testcase( mask!=0xffffffff && iCol==31 );
 testcase( mask!=0xffffffff && iCol==32 );
 if( mask==0xffffffff || (iCol<=31 && (mask & MASKBIT32(iCol))!=0) ){
 int kk = sqlite3TableColumnToStorage(pTab, iCol);
 sqlite3ExprCodeGetColumnOfTable(v, pTab, iDataCur, iCol, iOld+kk+1);
 }
 }

 /* Invoke BEFORE DELETE trigger programs. */
 addrStart = sqlite3VdbeCurrentAddr(v);
 sqlite3CodeRowTrigger(pParse, pTrigger,
 TK_DELETE, 0, TRIGGER_BEFORE, pTab, iOld, onconf, iLabel
 );

 /* If any BEFORE triggers were coded, then seek the cursor to the
 ** row to be deleted again. It may be that the BEFORE triggers moved
 ** the cursor or already deleted the row that the cursor was
 ** pointing to.
 **
 ** Also disable the iIdxNoSeek optimization since the BEFORE trigger
 ** may have moved that cursor.
 */
 if( addrStart<sqlite3VdbeCurrentAddr(v) ){
 sqlite3VdbeAddOp4Int(v, opSeek, iDataCur, iLabel, iPk, nPk);
 VdbeCoverageIf(v, opSeek==OP_NotExists);
 VdbeCoverageIf(v, opSeek==OP_NotFound);
 testcase( iIdxNoSeek>=0 );
 iIdxNoSeek = -1;
 }

 /* Do FK processing. This call checks that any FK constraints that
 ** refer to this table (i.e. constraints attached to other tables)
 ** are not violated by deleting this row. */
 sqlite3FkCheck(pParse, pTab, iOld, 0, 0, 0);
 }

 /* Delete the index and table entries. Skip this step if pTab is really
 ** a view (in which case the only effect of the DELETE statement is to
 ** fire the INSTEAD OF triggers). 
 **
 ** If variable 'count' is non-zero, then this OP_Delete instruction should
 ** invoke the update-hook. The pre-update-hook, on the other hand should
 ** be invoked unless table pTab is a system table. The difference is that
 ** the update-hook is not invoked for rows removed by REPLACE, but the
 ** pre-update-hook is.
 */
 if( !IsView(pTab) ){
 u8 p5 = 0;
 sqlite3GenerateRowIndexDelete(pParse, pTab, iDataCur, iIdxCur,0,iIdxNoSeek);
 sqlite3VdbeAddOp2(v, OP_Delete, iDataCur, (count?OPFLAG_NCHANGE:0));
 if( pParse->nested==0 || 0==sqlite3_stricmp(pTab->zName, "sqlite_stat1") ){
 sqlite3VdbeAppendP4(v, (char*)pTab, P4_TABLE);
 }
 if( eMode!=ONEPASS_OFF ){
 sqlite3VdbeChangeP5(v, OPFLAG_AUXDELETE);
 }
 if( iIdxNoSeek>=0 && iIdxNoSeek!=iDataCur ){
 sqlite3VdbeAddOp1(v, OP_Delete, iIdxNoSeek);
 }
 if( eMode==ONEPASS_MULTI ) p5 |= OPFLAG_SAVEPOSITION;
 sqlite3VdbeChangeP5(v, p5);
 }

 /* Do any ON CASCADE, SET NULL or SET DEFAULT operations required to
 ** handle rows (possibly in other tables) that refer via a foreign key
 ** to the row just deleted. */
 sqlite3FkActions(pParse, pTab, 0, iOld, 0, 0);

 /* Invoke AFTER DELETE trigger programs. */
 if( pTrigger ){
 sqlite3CodeRowTrigger(pParse, pTrigger,
 TK_DELETE, 0, TRIGGER_AFTER, pTab, iOld, onconf, iLabel
 );
 }

 /* Jump here if the row had already been deleted before any BEFORE
 ** trigger programs were invoked. Or if a trigger program throws a
 ** RAISE(IGNORE) exception. */
 sqlite3VdbeResolveLabel(v, iLabel);
 VdbeModuleComment((v, "END: GenRowDel()"));
}

/*
** This routine generates VDBE code that causes the deletion of all
** index entries associated with a single row of a single table, pTab
**
** Preconditions:
**
** 1. A read/write cursor "iDataCur" must be open on the canonical storage
** btree for the table pTab. (This will be either the table itself
** for rowid tables or to the primary key index for WITHOUT ROWID
** tables.)
**
** 2. Read/write cursors for all indices of pTab must be open as
** cursor number iIdxCur+i for the i-th index. (The pTab->pIndex
** index is the 0-th index.)
**
** 3. The "iDataCur" cursor must be already be positioned on the row
** that is to be deleted.
*/
void sqlite3GenerateRowIndexDelete(
 Parse *pParse, /* Parsing and code generating context */
 Table *pTab, /* Table containing the row to be deleted */
 int iDataCur, /* Cursor of table holding data. */
 int iIdxCur, /* First index cursor */
 int *aRegIdx, /* Only delete if aRegIdx!=0 && aRegIdx[i]>0 */
 int iIdxNoSeek /* Do not delete from this cursor */
){
 int i; /* Index loop counter */
 int r1 = -1; /* Register holding an index key */
 int iPartIdxLabel; /* Jump destination for skipping partial index entries */
 Index *pIdx; /* Current index */
 Index *pPrior = 0; /* Prior index */
 Vdbe *v; /* The prepared statement under construction */
 Index *pPk; /* PRIMARY KEY index, or NULL for rowid tables */

 v = pParse->pVdbe;
 pPk = HasRowid(pTab) ? 0 : sqlite3PrimaryKeyIndex(pTab);
 for(i=0, pIdx=pTab->pIndex; pIdx; i++, pIdx=pIdx->pNext){
 assert( iIdxCur+i!=iDataCur || pPk==pIdx );
 if( aRegIdx!=0 && aRegIdx[i]==0 ) continue;
 if( pIdx==pPk ) continue;
 if( iIdxCur+i==iIdxNoSeek ) continue;
 VdbeModuleComment((v, "GenRowIdxDel for %s", pIdx->zName));
 r1 = sqlite3GenerateIndexKey(pParse, pIdx, iDataCur, 0, 1,
 &iPartIdxLabel, pPrior, r1);
 sqlite3VdbeAddOp3(v, OP_IdxDelete, iIdxCur+i, r1,
 pIdx->uniqNotNull ? pIdx->nKeyCol : pIdx->nColumn);
 sqlite3ResolvePartIdxLabel(pParse, iPartIdxLabel);
 pPrior = pIdx;
 }
}

/*
** Generate code that will assemble an index key and stores it in register
** regOut. The key with be for index pIdx which is an index on pTab.
** iCur is the index of a cursor open on the pTab table and pointing to
** the entry that needs indexing. If pTab is a WITHOUT ROWID table, then
** iCur must be the cursor of the PRIMARY KEY index.
**
** Return a register number which is the first in a block of
** registers that holds the elements of the index key. The
** block of registers has already been deallocated by the time
** this routine returns.
**
** If *piPartIdxLabel is not NULL, fill it in with a label and jump
** to that label if pIdx is a partial index that should be skipped.
** The label should be resolved using sqlite3ResolvePartIdxLabel().
** A partial index should be skipped if its WHERE clause evaluates
** to false or null. If pIdx is not a partial index, *piPartIdxLabel
** will be set to zero which is an empty label that is ignored by
** sqlite3ResolvePartIdxLabel().
**
** The pPrior and regPrior parameters are used to implement a cache to
** avoid unnecessary register loads. If pPrior is not NULL, then it is
** a pointer to a different index for which an index key has just been
** computed into register regPrior. If the current pIdx index is generating
** its key into the same sequence of registers and if pPrior and pIdx share
** a column in common, then the register corresponding to that column already
** holds the correct value and the loading of that register is skipped.
** This optimization is helpful when doing a DELETE or an INTEGRITY_CHECK
** on a table with multiple indices, and especially with the ROWID or
** PRIMARY KEY columns of the index.
*/
int sqlite3GenerateIndexKey(
 Parse *pParse, /* Parsing context */
 Index *pIdx, /* The index for which to generate a key */
 int iDataCur, /* Cursor number from which to take column data */
 int regOut, /* Put the new key into this register if not 0 */
 int prefixOnly, /* Compute only a unique prefix of the key */
 int *piPartIdxLabel, /* OUT: Jump to this label to skip partial index */
 Index *pPrior, /* Previously generated index key */
 int regPrior /* Register holding previous generated key */
){
 Vdbe *v = pParse->pVdbe;
 int j;
 int regBase;
 int nCol;

 if( piPartIdxLabel ){
 if( pIdx->pPartIdxWhere ){
 *piPartIdxLabel = sqlite3VdbeMakeLabel(pParse);
 pParse->iSelfTab = iDataCur + 1;
 sqlite3ExprIfFalseDup(pParse, pIdx->pPartIdxWhere, *piPartIdxLabel,
 SQLITE_JUMPIFNULL);
 pParse->iSelfTab = 0;
 pPrior = 0; /* Ticket a9efb42811fa41ee 2019年11月02日;
 ** pPartIdxWhere may have corrupted regPrior registers */
 }else{
 *piPartIdxLabel = 0;
 }
 }
 nCol = (prefixOnly && pIdx->uniqNotNull) ? pIdx->nKeyCol : pIdx->nColumn;
 regBase = sqlite3GetTempRange(pParse, nCol);
 if( pPrior && (regBase!=regPrior || pPrior->pPartIdxWhere) ) pPrior = 0;
 for(j=0; j<nCol; j++){
 if( pPrior
 && pPrior->aiColumn[j]==pIdx->aiColumn[j]
 && pPrior->aiColumn[j]!=XN_EXPR
 ){
 /* This column was already computed by the previous index */
 continue;
 }
 sqlite3ExprCodeLoadIndexColumn(pParse, pIdx, iDataCur, j, regBase+j);
 if( pIdx->aiColumn[j]>=0 ){
 /* If the column affinity is REAL but the number is an integer, then it
 ** might be stored in the table as an integer (using a compact
 ** representation) then converted to REAL by an OP_RealAffinity opcode.
 ** But we are getting ready to store this value back into an index, where
 ** it should be converted by to INTEGER again. So omit the
 ** OP_RealAffinity opcode if it is present */
 sqlite3VdbeDeletePriorOpcode(v, OP_RealAffinity);
 }
 }
 if( regOut ){
 sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase, nCol, regOut);
 }
 sqlite3ReleaseTempRange(pParse, regBase, nCol);
 return regBase;
}

/*
** If a prior call to sqlite3GenerateIndexKey() generated a jump-over label
** because it was a partial index, then this routine should be called to
** resolve that label.
*/
void sqlite3ResolvePartIdxLabel(Parse *pParse, int iLabel){
 if( iLabel ){
 sqlite3VdbeResolveLabel(pParse->pVdbe, iLabel);
 }
}