509 lines
16 KiB
C
509 lines
16 KiB
C
/*
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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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** $Id$
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*/
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#include "sqliteInt.h"
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/*
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** The most recently coded instruction was an OP_Column to retrieve the
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** i-th column of table pTab. This routine sets the P3 parameter of the
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** OP_Column to the default value, if any.
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**
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** The default value of a column is specified by a DEFAULT clause in the
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** column definition. This was either supplied by the user when the table
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** was created, or added later to the table definition by an ALTER TABLE
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** command. If the latter, then the row-records in the table btree on disk
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** may not contain a value for the column and the default value, taken
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** from the P3 parameter of the OP_Column instruction, is returned instead.
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** If the former, then all row-records are guaranteed to include a value
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** for the column and the P3 value is not required.
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**
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** Column definitions created by an ALTER TABLE command may only have
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** literal default values specified: a number, null or a string. (If a more
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** complicated default expression value was provided, it is evaluated
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** when the ALTER TABLE is executed and one of the literal values written
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** into the sqlite_master table.)
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**
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** Therefore, the P3 parameter is only required if the default value for
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** the column is a literal number, string or null. The sqlite3ValueFromExpr()
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** function is capable of transforming these types of expressions into
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** sqlite3_value objects.
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*/
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void sqlite3ColumnDefault(Vdbe *v, Table *pTab, int i){
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if( pTab && !pTab->pSelect ){
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sqlite3_value *pValue;
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u8 enc = ENC(sqlite3VdbeDb(v));
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Column *pCol = &pTab->aCol[i];
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sqlite3ValueFromExpr(pCol->pDflt, enc, pCol->affinity, &pValue);
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if( pValue ){
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sqlite3VdbeChangeP3(v, -1, (const char *)pValue, P3_MEM);
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}else{
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VdbeComment((v, "# %s.%s", pTab->zName, pCol->zName));
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}
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}
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}
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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 sqlite3Update(
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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 = 0; /* 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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sqlite3 *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 chngRowid; /* True if the record number is being changed */
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Expr *pRowidExpr = 0; /* Expression defining the new record number */
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int openAll = 0; /* True if all indices need to be opened */
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AuthContext sContext; /* The authorization context */
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NameContext sNC; /* The name-context to resolve expressions in */
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int iDb; /* Database containing the table being updated */
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#ifndef SQLITE_OMIT_TRIGGER
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int isView; /* Trying to update a view */
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int triggers_exist = 0; /* True if any row triggers exist */
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#endif
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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 || sqlite3MallocFailed() ){
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goto update_cleanup;
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}
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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 = sqlite3SrcListLookup(pParse, pTabList);
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if( pTab==0 ) goto update_cleanup;
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iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
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/* Figure out if we have any triggers and if the table being
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** updated is a view
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*/
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#ifndef SQLITE_OMIT_TRIGGER
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triggers_exist = sqlite3TriggersExist(pParse, pTab, TK_UPDATE, pChanges);
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isView = pTab->pSelect!=0;
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#else
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# define triggers_exist 0
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# define isView 0
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#endif
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#ifdef SQLITE_OMIT_VIEW
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# undef isView
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# define isView 0
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#endif
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if( sqlite3IsReadOnly(pParse, pTab, triggers_exist) ){
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goto update_cleanup;
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}
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if( isView ){
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if( sqlite3ViewGetColumnNames(pParse, pTab) ){
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goto update_cleanup;
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}
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}
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aXRef = sqliteMallocRaw( 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( 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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/* Initialize the name-context */
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memset(&sNC, 0, sizeof(sNC));
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sNC.pParse = pParse;
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sNC.pSrcList = pTabList;
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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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chngRowid = 0;
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for(i=0; i<pChanges->nExpr; i++){
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if( sqlite3ExprResolveNames(&sNC, pChanges->a[i].pExpr) ){
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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( sqlite3StrICmp(pTab->aCol[j].zName, pChanges->a[i].zName)==0 ){
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if( j==pTab->iPKey ){
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chngRowid = 1;
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pRowidExpr = 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( sqlite3IsRowid(pChanges->a[i].zName) ){
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chngRowid = 1;
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pRowidExpr = pChanges->a[i].pExpr;
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}else{
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sqlite3ErrorMsg(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 = sqlite3AuthCheck(pParse, SQLITE_UPDATE, pTab->zName,
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pTab->aCol[j].zName, db->aDb[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( chngRowid ){
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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 = sqliteMallocRaw( 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( chngRowid ){
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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( sqlite3ExprResolveNames(&sNC, pWhere) ){
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goto update_cleanup;
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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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sqlite3AuthContextPush(pParse, &sContext, pTab->zName);
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}
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/* Begin generating code.
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*/
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v = sqlite3GetVdbe(pParse);
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if( v==0 ) goto update_cleanup;
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if( pParse->nested==0 ) sqlite3VdbeCountChanges(v);
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sqlite3BeginWriteOperation(pParse, 1, iDb);
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/* If we are trying to update a view, realize that view into
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** a ephemeral table.
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*/
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if( isView ){
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Select *pView;
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pView = sqlite3SelectDup(pTab->pSelect);
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sqlite3Select(pParse, pView, SRT_VirtualTab, iCur, 0, 0, 0, 0);
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sqlite3SelectDelete(pView);
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}
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/* Begin the database scan
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*/
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pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 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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sqlite3VdbeAddOp(v, OP_Rowid, iCur, 0);
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sqlite3VdbeAddOp(v, OP_FifoWrite, 0, 0);
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/* End the database scan loop.
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*/
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sqlite3WhereEnd(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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sqlite3VdbeAddOp(v, OP_Integer, 0, 0);
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}
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if( triggers_exist ){
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/* Create pseudo-tables for NEW and OLD
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*/
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sqlite3VdbeAddOp(v, OP_OpenPseudo, oldIdx, 0);
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sqlite3VdbeAddOp(v, OP_SetNumColumns, oldIdx, pTab->nCol);
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sqlite3VdbeAddOp(v, OP_OpenPseudo, newIdx, 0);
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sqlite3VdbeAddOp(v, OP_SetNumColumns, newIdx, pTab->nCol);
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/* The top of the update loop for when there are triggers.
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*/
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addr = sqlite3VdbeAddOp(v, OP_FifoRead, 0, 0);
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if( !isView ){
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sqlite3VdbeAddOp(v, OP_Dup, 0, 0);
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sqlite3VdbeAddOp(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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sqlite3OpenTable(pParse, iCur, iDb, pTab, OP_OpenRead);
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}
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sqlite3VdbeAddOp(v, OP_MoveGe, iCur, 0);
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/* Generate the OLD table
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*/
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sqlite3VdbeAddOp(v, OP_Rowid, iCur, 0);
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sqlite3VdbeAddOp(v, OP_RowData, iCur, 0);
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sqlite3VdbeAddOp(v, OP_Insert, oldIdx, 0);
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/* Generate the NEW table
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*/
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if( chngRowid ){
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sqlite3ExprCodeAndCache(pParse, pRowidExpr);
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}else{
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sqlite3VdbeAddOp(v, OP_Rowid, 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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sqlite3VdbeAddOp(v, OP_Null, 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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sqlite3VdbeAddOp(v, OP_Column, iCur, i);
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sqlite3ColumnDefault(v, pTab, i);
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}else{
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sqlite3ExprCodeAndCache(pParse, pChanges->a[j].pExpr);
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}
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}
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sqlite3VdbeAddOp(v, OP_MakeRecord, pTab->nCol, 0);
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if( !isView ){
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sqlite3TableAffinityStr(v, pTab);
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}
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if( pParse->nErr ) goto update_cleanup;
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sqlite3VdbeAddOp(v, OP_Insert, newIdx, 0);
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if( !isView ){
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sqlite3VdbeAddOp(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( sqlite3CodeRowTrigger(pParse, TK_UPDATE, pChanges, TRIGGER_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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sqlite3OpenTable(pParse, iCur, iDb, pTab, OP_OpenWrite);
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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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KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIdx);
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sqlite3VdbeAddOp(v, OP_Integer, iDb, 0);
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sqlite3VdbeOp3(v, OP_OpenWrite, iCur+i+1, pIdx->tnum,
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(char*)pKey, P3_KEYINFO_HANDOFF);
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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( !triggers_exist ){
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addr = sqlite3VdbeAddOp(v, OP_FifoRead, 0, 0);
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sqlite3VdbeAddOp(v, OP_Dup, 0, 0);
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}
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sqlite3VdbeAddOp(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( chngRowid ){
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sqlite3ExprCode(pParse, pRowidExpr);
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sqlite3VdbeAddOp(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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sqlite3VdbeAddOp(v, OP_Null, 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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sqlite3VdbeAddOp(v, OP_Column, iCur, i);
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sqlite3ColumnDefault(v, pTab, i);
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}else{
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sqlite3ExprCode(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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sqlite3GenerateConstraintChecks(pParse, pTab, iCur, aIdxUsed, chngRowid, 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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sqlite3GenerateRowIndexDelete(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( chngRowid ){
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sqlite3VdbeAddOp(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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sqlite3CompleteInsertion(pParse, pTab, iCur, aIdxUsed, chngRowid, 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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sqlite3VdbeAddOp(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( 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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sqlite3VdbeAddOp(v, OP_Close, iCur+i+1, 0);
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}
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sqlite3VdbeAddOp(v, OP_Close, iCur, 0);
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}
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if( sqlite3CodeRowTrigger(pParse, TK_UPDATE, pChanges, TRIGGER_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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|
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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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sqlite3VdbeAddOp(v, OP_Goto, 0, addr);
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sqlite3VdbeJumpHere(v, addr);
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|
/* Close all tables if there were no FOR EACH ROW triggers */
|
|
if( !triggers_exist ){
|
|
for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
|
|
if( openAll || aIdxUsed[i] ){
|
|
sqlite3VdbeAddOp(v, OP_Close, iCur+i+1, 0);
|
|
}
|
|
}
|
|
sqlite3VdbeAddOp(v, OP_Close, iCur, 0);
|
|
}else{
|
|
sqlite3VdbeAddOp(v, OP_Close, newIdx, 0);
|
|
sqlite3VdbeAddOp(v, OP_Close, oldIdx, 0);
|
|
}
|
|
|
|
/*
|
|
** Return the number of rows that were changed. If this routine is
|
|
** generating code because of a call to sqlite3NestedParse(), do not
|
|
** invoke the callback function.
|
|
*/
|
|
if( db->flags & SQLITE_CountRows && !pParse->trigStack && pParse->nested==0 ){
|
|
sqlite3VdbeAddOp(v, OP_Callback, 1, 0);
|
|
sqlite3VdbeSetNumCols(v, 1);
|
|
sqlite3VdbeSetColName(v, 0, COLNAME_NAME, "rows updated", P3_STATIC);
|
|
}
|
|
|
|
update_cleanup:
|
|
sqlite3AuthContextPop(&sContext);
|
|
sqliteFree(apIdx);
|
|
sqliteFree(aXRef);
|
|
sqlite3SrcListDelete(pTabList);
|
|
sqlite3ExprListDelete(pChanges);
|
|
sqlite3ExprDelete(pWhere);
|
|
return;
|
|
}
|