453 lines
14 KiB
C
Executable File
453 lines
14 KiB
C
Executable File
/*
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** 2001 September 15
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**
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** The author disclaims copyright to this source code. In place of
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** a legal notice, here is a blessing:
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**
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** May you do good and not evil.
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** May you find forgiveness for yourself and forgive others.
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** May you share freely, never taking more than you give.
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**
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*************************************************************************
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** This file contains C code routines that are called by the parser
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** to handle UPDATE statements.
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**
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** $Id: update.c,v 1.1.1.1 2004-03-11 22:22:22 alex Exp $
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*/
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#include "sqliteInt.h"
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/*
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** Process an UPDATE statement.
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**
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** UPDATE OR IGNORE table_wxyz SET a=b, c=d WHERE e<5 AND f NOT NULL;
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** \_______/ \________/ \______/ \________________/
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* onError pTabList pChanges pWhere
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*/
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void sqliteUpdate(
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Parse *pParse, /* The parser context */
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SrcList *pTabList, /* The table in which we should change things */
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ExprList *pChanges, /* Things to be changed */
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Expr *pWhere, /* The WHERE clause. May be null */
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int onError /* How to handle constraint errors */
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){
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int i, j; /* Loop counters */
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Table *pTab; /* The table to be updated */
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int addr; /* VDBE instruction address of the start of the loop */
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WhereInfo *pWInfo; /* Information about the WHERE clause */
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Vdbe *v; /* The virtual database engine */
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Index *pIdx; /* For looping over indices */
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int nIdx; /* Number of indices that need updating */
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int nIdxTotal; /* Total number of indices */
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int iCur; /* VDBE Cursor number of pTab */
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sqlite *db; /* The database structure */
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Index **apIdx = 0; /* An array of indices that need updating too */
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char *aIdxUsed = 0; /* aIdxUsed[i]==1 if the i-th index is used */
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int *aXRef = 0; /* aXRef[i] is the index in pChanges->a[] of the
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** an expression for the i-th column of the table.
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** aXRef[i]==-1 if the i-th column is not changed. */
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int chngRecno; /* True if the record number is being changed */
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Expr *pRecnoExpr; /* Expression defining the new record number */
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int openAll; /* True if all indices need to be opened */
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int isView; /* Trying to update a view */
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AuthContext sContext; /* The authorization context */
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int before_triggers; /* True if there are any BEFORE triggers */
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int after_triggers; /* True if there are any AFTER triggers */
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int row_triggers_exist = 0; /* True if any row triggers exist */
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int newIdx = -1; /* index of trigger "new" temp table */
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int oldIdx = -1; /* index of trigger "old" temp table */
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sContext.pParse = 0;
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if( pParse->nErr || sqlite_malloc_failed ) goto update_cleanup;
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db = pParse->db;
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assert( pTabList->nSrc==1 );
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/* Locate the table which we want to update.
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*/
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pTab = sqliteSrcListLookup(pParse, pTabList);
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if( pTab==0 ) goto update_cleanup;
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before_triggers = sqliteTriggersExist(pParse, pTab->pTrigger,
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TK_UPDATE, TK_BEFORE, TK_ROW, pChanges);
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after_triggers = sqliteTriggersExist(pParse, pTab->pTrigger,
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TK_UPDATE, TK_AFTER, TK_ROW, pChanges);
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row_triggers_exist = before_triggers || after_triggers;
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isView = pTab->pSelect!=0;
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if( sqliteIsReadOnly(pParse, pTab, before_triggers) ){
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goto update_cleanup;
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}
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if( isView ){
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if( sqliteViewGetColumnNames(pParse, pTab) ){
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goto update_cleanup;
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}
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}
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aXRef = sqliteMalloc( sizeof(int) * pTab->nCol );
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if( aXRef==0 ) goto update_cleanup;
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for(i=0; i<pTab->nCol; i++) aXRef[i] = -1;
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/* If there are FOR EACH ROW triggers, allocate cursors for the
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** special OLD and NEW tables
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*/
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if( row_triggers_exist ){
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newIdx = pParse->nTab++;
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oldIdx = pParse->nTab++;
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}
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/* Allocate a cursors for the main database table and for all indices.
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** The index cursors might not be used, but if they are used they
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** need to occur right after the database cursor. So go ahead and
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** allocate enough space, just in case.
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*/
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pTabList->a[0].iCursor = iCur = pParse->nTab++;
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for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
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pParse->nTab++;
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}
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/* Resolve the column names in all the expressions of the
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** of the UPDATE statement. Also find the column index
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** for each column to be updated in the pChanges array. For each
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** column to be updated, make sure we have authorization to change
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** that column.
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*/
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chngRecno = 0;
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for(i=0; i<pChanges->nExpr; i++){
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if( sqliteExprResolveIds(pParse, pTabList, 0, pChanges->a[i].pExpr) ){
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goto update_cleanup;
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}
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if( sqliteExprCheck(pParse, pChanges->a[i].pExpr, 0, 0) ){
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goto update_cleanup;
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}
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for(j=0; j<pTab->nCol; j++){
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if( sqliteStrICmp(pTab->aCol[j].zName, pChanges->a[i].zName)==0 ){
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if( j==pTab->iPKey ){
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chngRecno = 1;
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pRecnoExpr = pChanges->a[i].pExpr;
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}
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aXRef[j] = i;
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break;
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}
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}
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if( j>=pTab->nCol ){
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if( sqliteIsRowid(pChanges->a[i].zName) ){
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chngRecno = 1;
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pRecnoExpr = pChanges->a[i].pExpr;
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}else{
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sqliteErrorMsg(pParse, "no such column: %s", pChanges->a[i].zName);
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goto update_cleanup;
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}
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}
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#ifndef SQLITE_OMIT_AUTHORIZATION
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{
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int rc;
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rc = sqliteAuthCheck(pParse, SQLITE_UPDATE, pTab->zName,
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pTab->aCol[j].zName, db->aDb[pTab->iDb].zName);
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if( rc==SQLITE_DENY ){
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goto update_cleanup;
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}else if( rc==SQLITE_IGNORE ){
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aXRef[j] = -1;
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}
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}
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#endif
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}
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/* Allocate memory for the array apIdx[] and fill it with pointers to every
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** index that needs to be updated. Indices only need updating if their
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** key includes one of the columns named in pChanges or if the record
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** number of the original table entry is changing.
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*/
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for(nIdx=nIdxTotal=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, nIdxTotal++){
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if( chngRecno ){
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i = 0;
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}else {
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for(i=0; i<pIdx->nColumn; i++){
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if( aXRef[pIdx->aiColumn[i]]>=0 ) break;
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}
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}
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if( i<pIdx->nColumn ) nIdx++;
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}
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if( nIdxTotal>0 ){
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apIdx = sqliteMalloc( sizeof(Index*) * nIdx + nIdxTotal );
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if( apIdx==0 ) goto update_cleanup;
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aIdxUsed = (char*)&apIdx[nIdx];
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}
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for(nIdx=j=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, j++){
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if( chngRecno ){
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i = 0;
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}else{
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for(i=0; i<pIdx->nColumn; i++){
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if( aXRef[pIdx->aiColumn[i]]>=0 ) break;
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}
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}
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if( i<pIdx->nColumn ){
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apIdx[nIdx++] = pIdx;
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aIdxUsed[j] = 1;
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}else{
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aIdxUsed[j] = 0;
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}
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}
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/* Resolve the column names in all the expressions in the
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** WHERE clause.
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*/
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if( pWhere ){
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if( sqliteExprResolveIds(pParse, pTabList, 0, pWhere) ){
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goto update_cleanup;
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}
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if( sqliteExprCheck(pParse, pWhere, 0, 0) ){
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goto update_cleanup;
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}
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}
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/* Start the view context
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*/
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if( isView ){
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sqliteAuthContextPush(pParse, &sContext, pTab->zName);
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}
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/* Begin generating code.
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*/
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v = sqliteGetVdbe(pParse);
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if( v==0 ) goto update_cleanup;
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sqliteBeginWriteOperation(pParse, 1, pTab->iDb);
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/* If we are trying to update a view, construct that view into
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** a temporary table.
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*/
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if( isView ){
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Select *pView;
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pView = sqliteSelectDup(pTab->pSelect);
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sqliteSelect(pParse, pView, SRT_TempTable, iCur, 0, 0, 0);
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sqliteSelectDelete(pView);
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}
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/* Begin the database scan
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*/
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pWInfo = sqliteWhereBegin(pParse, pTabList, pWhere, 1, 0);
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if( pWInfo==0 ) goto update_cleanup;
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/* Remember the index of every item to be updated.
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*/
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sqliteVdbeAddOp(v, OP_ListWrite, 0, 0);
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/* End the database scan loop.
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*/
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sqliteWhereEnd(pWInfo);
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/* Initialize the count of updated rows
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*/
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if( db->flags & SQLITE_CountRows && !pParse->trigStack ){
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sqliteVdbeAddOp(v, OP_Integer, 0, 0);
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}
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if( row_triggers_exist ){
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/* Create pseudo-tables for NEW and OLD
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*/
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sqliteVdbeAddOp(v, OP_OpenPseudo, oldIdx, 0);
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sqliteVdbeAddOp(v, OP_OpenPseudo, newIdx, 0);
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/* The top of the update loop for when there are triggers.
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*/
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sqliteVdbeAddOp(v, OP_ListRewind, 0, 0);
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addr = sqliteVdbeAddOp(v, OP_ListRead, 0, 0);
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sqliteVdbeAddOp(v, OP_Dup, 0, 0);
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/* Open a cursor and make it point to the record that is
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** being updated.
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*/
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sqliteVdbeAddOp(v, OP_Dup, 0, 0);
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if( !isView ){
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sqliteVdbeAddOp(v, OP_Integer, pTab->iDb, 0);
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sqliteVdbeAddOp(v, OP_OpenRead, iCur, pTab->tnum);
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}
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sqliteVdbeAddOp(v, OP_MoveTo, iCur, 0);
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/* Generate the OLD table
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*/
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sqliteVdbeAddOp(v, OP_Recno, iCur, 0);
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sqliteVdbeAddOp(v, OP_RowData, iCur, 0);
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sqliteVdbeAddOp(v, OP_PutIntKey, oldIdx, 0);
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/* Generate the NEW table
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*/
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if( chngRecno ){
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sqliteExprCode(pParse, pRecnoExpr);
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}else{
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sqliteVdbeAddOp(v, OP_Recno, iCur, 0);
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}
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for(i=0; i<pTab->nCol; i++){
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if( i==pTab->iPKey ){
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sqliteVdbeAddOp(v, OP_String, 0, 0);
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continue;
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}
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j = aXRef[i];
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if( j<0 ){
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sqliteVdbeAddOp(v, OP_Column, iCur, i);
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}else{
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sqliteExprCode(pParse, pChanges->a[j].pExpr);
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}
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}
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sqliteVdbeAddOp(v, OP_MakeRecord, pTab->nCol, 0);
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sqliteVdbeAddOp(v, OP_PutIntKey, newIdx, 0);
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if( !isView ){
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sqliteVdbeAddOp(v, OP_Close, iCur, 0);
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}
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/* Fire the BEFORE and INSTEAD OF triggers
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*/
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if( sqliteCodeRowTrigger(pParse, TK_UPDATE, pChanges, TK_BEFORE, pTab,
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newIdx, oldIdx, onError, addr) ){
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goto update_cleanup;
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}
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}
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if( !isView ){
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/*
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** Open every index that needs updating. Note that if any
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** index could potentially invoke a REPLACE conflict resolution
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** action, then we need to open all indices because we might need
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** to be deleting some records.
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*/
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sqliteVdbeAddOp(v, OP_Integer, pTab->iDb, 0);
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sqliteVdbeAddOp(v, OP_OpenWrite, iCur, pTab->tnum);
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if( onError==OE_Replace ){
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openAll = 1;
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}else{
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openAll = 0;
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for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
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if( pIdx->onError==OE_Replace ){
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openAll = 1;
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break;
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}
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}
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}
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for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
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if( openAll || aIdxUsed[i] ){
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sqliteVdbeAddOp(v, OP_Integer, pIdx->iDb, 0);
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sqliteVdbeAddOp(v, OP_OpenWrite, iCur+i+1, pIdx->tnum);
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assert( pParse->nTab>iCur+i+1 );
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}
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}
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/* Loop over every record that needs updating. We have to load
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** the old data for each record to be updated because some columns
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** might not change and we will need to copy the old value.
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** Also, the old data is needed to delete the old index entires.
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** So make the cursor point at the old record.
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*/
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if( !row_triggers_exist ){
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sqliteVdbeAddOp(v, OP_ListRewind, 0, 0);
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addr = sqliteVdbeAddOp(v, OP_ListRead, 0, 0);
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sqliteVdbeAddOp(v, OP_Dup, 0, 0);
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}
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sqliteVdbeAddOp(v, OP_NotExists, iCur, addr);
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/* If the record number will change, push the record number as it
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** will be after the update. (The old record number is currently
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** on top of the stack.)
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*/
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if( chngRecno ){
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sqliteExprCode(pParse, pRecnoExpr);
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sqliteVdbeAddOp(v, OP_MustBeInt, 0, 0);
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}
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/* Compute new data for this record.
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*/
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for(i=0; i<pTab->nCol; i++){
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if( i==pTab->iPKey ){
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sqliteVdbeAddOp(v, OP_String, 0, 0);
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continue;
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}
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j = aXRef[i];
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if( j<0 ){
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sqliteVdbeAddOp(v, OP_Column, iCur, i);
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}else{
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sqliteExprCode(pParse, pChanges->a[j].pExpr);
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}
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}
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/* Do constraint checks
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*/
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sqliteGenerateConstraintChecks(pParse, pTab, iCur, aIdxUsed, chngRecno, 1,
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onError, addr);
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/* Delete the old indices for the current record.
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*/
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sqliteGenerateRowIndexDelete(db, v, pTab, iCur, aIdxUsed);
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/* If changing the record number, delete the old record.
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*/
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if( chngRecno ){
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sqliteVdbeAddOp(v, OP_Delete, iCur, 0);
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}
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/* Create the new index entries and the new record.
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*/
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sqliteCompleteInsertion(pParse, pTab, iCur, aIdxUsed, chngRecno, 1, -1);
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}
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/* Increment the row counter
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*/
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if( db->flags & SQLITE_CountRows && !pParse->trigStack){
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sqliteVdbeAddOp(v, OP_AddImm, 1, 0);
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}
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/* If there are triggers, close all the cursors after each iteration
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** through the loop. The fire the after triggers.
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*/
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if( row_triggers_exist ){
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if( !isView ){
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for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
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if( openAll || aIdxUsed[i] )
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sqliteVdbeAddOp(v, OP_Close, iCur+i+1, 0);
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}
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sqliteVdbeAddOp(v, OP_Close, iCur, 0);
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pParse->nTab = iCur;
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}
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if( sqliteCodeRowTrigger(pParse, TK_UPDATE, pChanges, TK_AFTER, pTab,
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newIdx, oldIdx, onError, addr) ){
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goto update_cleanup;
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}
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}
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/* Repeat the above with the next record to be updated, until
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** all record selected by the WHERE clause have been updated.
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*/
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sqliteVdbeAddOp(v, OP_Goto, 0, addr);
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sqliteVdbeChangeP2(v, addr, sqliteVdbeCurrentAddr(v));
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sqliteVdbeAddOp(v, OP_ListReset, 0, 0);
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/* Close all tables if there were no FOR EACH ROW triggers */
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if( !row_triggers_exist ){
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for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
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if( openAll || aIdxUsed[i] ){
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sqliteVdbeAddOp(v, OP_Close, iCur+i+1, 0);
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}
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}
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sqliteVdbeAddOp(v, OP_Close, iCur, 0);
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pParse->nTab = iCur;
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}else{
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sqliteVdbeAddOp(v, OP_Close, newIdx, 0);
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sqliteVdbeAddOp(v, OP_Close, oldIdx, 0);
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}
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sqliteVdbeAddOp(v, OP_SetCounts, 0, 0);
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sqliteEndWriteOperation(pParse);
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/*
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** Return the number of rows that were changed.
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*/
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if( db->flags & SQLITE_CountRows && !pParse->trigStack ){
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sqliteVdbeOp3(v, OP_ColumnName, 0, 1, "rows updated", P3_STATIC);
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sqliteVdbeAddOp(v, OP_Callback, 1, 0);
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}
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update_cleanup:
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sqliteAuthContextPop(&sContext);
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sqliteFree(apIdx);
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sqliteFree(aXRef);
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sqliteSrcListDelete(pTabList);
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sqliteExprListDelete(pChanges);
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sqliteExprDelete(pWhere);
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return;
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}
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