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DEFINITIONS
This source file includes following definitions.
- sqliteUpdate
/*
** 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
** to handle UPDATE statements.
**
** $Id: update.c,v 1.5.4.1 2005/09/07 15:11:33 iliaa Exp $
*/
#include "sqliteInt.h"
/*
** Process an UPDATE statement.
**
** UPDATE OR IGNORE table_wxyz SET a=b, c=d WHERE e<5 AND f NOT NULL;
** \_______/ \________/ \______/ \________________/
* onError pTabList pChanges pWhere
*/
void sqliteUpdate(
Parse *pParse, /* The parser context */
SrcList *pTabList, /* The table in which we should change things */
ExprList *pChanges, /* Things to be changed */
Expr *pWhere, /* The WHERE clause. May be null */
int onError /* How to handle constraint errors */
){
int i, j; /* Loop counters */
Table *pTab; /* The table to be updated */
int loopStart; /* VDBE instruction address of the start of the loop */
int jumpInst; /* Addr of VDBE instruction to jump out of loop */
WhereInfo *pWInfo; /* Information about the WHERE clause */
Vdbe *v; /* The virtual database engine */
Index *pIdx; /* For looping over indices */
int nIdx; /* Number of indices that need updating */
int nIdxTotal; /* Total number of indices */
int iCur; /* VDBE Cursor number of pTab */
sqlite *db; /* The database structure */
Index **apIdx = 0; /* An array of indices that need updating too */
char *aIdxUsed = 0; /* aIdxUsed[i]==1 if the i-th index is used */
int *aXRef = 0; /* aXRef[i] is the index in pChanges->a[] of the
** an expression for the i-th column of the table.
** aXRef[i]==-1 if the i-th column is not changed. */
int chngRecno; /* True if the record number is being changed */
Expr *pRecnoExpr; /* Expression defining the new record number */
int openAll; /* True if all indices need to be opened */
int isView; /* Trying to update a view */
int iStackDepth; /* Index of memory cell holding stack depth */
AuthContext sContext; /* The authorization context */
int before_triggers; /* True if there are any BEFORE triggers */
int after_triggers; /* True if there are any AFTER triggers */
int row_triggers_exist = 0; /* True if any row triggers exist */
int newIdx = -1; /* index of trigger "new" temp table */
int oldIdx = -1; /* index of trigger "old" temp table */
sContext.pParse = 0;
if( pParse->nErr || sqlite_malloc_failed ) goto update_cleanup;
db = pParse->db;
assert( pTabList->nSrc==1 );
iStackDepth = pParse->nMem++;
/* Locate the table which we want to update.
*/
pTab = sqliteSrcListLookup(pParse, pTabList);
if( pTab==0 ) goto update_cleanup;
before_triggers = sqliteTriggersExist(pParse, pTab->pTrigger,
TK_UPDATE, TK_BEFORE, TK_ROW, pChanges);
after_triggers = sqliteTriggersExist(pParse, pTab->pTrigger,
TK_UPDATE, TK_AFTER, TK_ROW, pChanges);
row_triggers_exist = before_triggers || after_triggers;
isView = pTab->pSelect!=0;
if( sqliteIsReadOnly(pParse, pTab, before_triggers) ){
goto update_cleanup;
}
if( isView ){
if( sqliteViewGetColumnNames(pParse, pTab) ){
goto update_cleanup;
}
}
aXRef = sqliteMalloc( sizeof(int) * pTab->nCol );
if( aXRef==0 ) goto update_cleanup;
for(i=0; i<pTab->nCol; i++) aXRef[i] = -1;
/* If there are FOR EACH ROW triggers, allocate cursors for the
** special OLD and NEW tables
*/
if( row_triggers_exist ){
newIdx = pParse->nTab++;
oldIdx = pParse->nTab++;
}
/* Allocate a cursors for the main database table and for all indices.
** The index cursors might not be used, but if they are used they
** need to occur right after the database cursor. So go ahead and
** allocate enough space, just in case.
*/
pTabList->a[0].iCursor = iCur = pParse->nTab++;
for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
pParse->nTab++;
}
/* Resolve the column names in all the expressions of the
** of the UPDATE statement. Also find the column index
** for each column to be updated in the pChanges array. For each
** column to be updated, make sure we have authorization to change
** that column.
*/
chngRecno = 0;
for(i=0; i<pChanges->nExpr; i++){
if( sqliteExprResolveIds(pParse, pTabList, 0, pChanges->a[i].pExpr) ){
goto update_cleanup;
}
if( sqliteExprCheck(pParse, pChanges->a[i].pExpr, 0, 0) ){
goto update_cleanup;
}
for(j=0; j<pTab->nCol; j++){
if( sqliteStrICmp(pTab->aCol[j].zName, pChanges->a[i].zName)==0 ){
if( j==pTab->iPKey ){
chngRecno = 1;
pRecnoExpr = pChanges->a[i].pExpr;
}
aXRef[j] = i;
break;
}
}
if( j>=pTab->nCol ){
if( sqliteIsRowid(pChanges->a[i].zName) ){
chngRecno = 1;
pRecnoExpr = pChanges->a[i].pExpr;
}else{
sqliteErrorMsg(pParse, "no such column: %s", pChanges->a[i].zName);
goto update_cleanup;
}
}
#ifndef SQLITE_OMIT_AUTHORIZATION
{
int rc;
rc = sqliteAuthCheck(pParse, SQLITE_UPDATE, pTab->zName,
pTab->aCol[j].zName, db->aDb[pTab->iDb].zName);
if( rc==SQLITE_DENY ){
goto update_cleanup;
}else if( rc==SQLITE_IGNORE ){
aXRef[j] = -1;
}
}
#endif
}
/* Allocate memory for the array apIdx[] and fill it with pointers to every
** index that needs to be updated. Indices only need updating if their
** key includes one of the columns named in pChanges or if the record
** number of the original table entry is changing.
*/
for(nIdx=nIdxTotal=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, nIdxTotal++){
if( chngRecno ){
i = 0;
}else {
for(i=0; i<pIdx->nColumn; i++){
if( aXRef[pIdx->aiColumn[i]]>=0 ) break;
}
}
if( i<pIdx->nColumn ) nIdx++;
}
if( nIdxTotal>0 ){
apIdx = sqliteMalloc( sizeof(Index*) * nIdx + nIdxTotal );
if( apIdx==0 ) goto update_cleanup;
aIdxUsed = (char*)&apIdx[nIdx];
}
for(nIdx=j=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, j++){
if( chngRecno ){
i = 0;
}else{
for(i=0; i<pIdx->nColumn; i++){
if( aXRef[pIdx->aiColumn[i]]>=0 ) break;
}
}
if( i<pIdx->nColumn ){
apIdx[nIdx++] = pIdx;
aIdxUsed[j] = 1;
}else{
aIdxUsed[j] = 0;
}
}
/* Resolve the column names in all the expressions in the
** WHERE clause.
*/
if( pWhere ){
if( sqliteExprResolveIds(pParse, pTabList, 0, pWhere) ){
goto update_cleanup;
}
if( sqliteExprCheck(pParse, pWhere, 0, 0) ){
goto update_cleanup;
}
}
/* Start the view context
*/
if( isView ){
sqliteAuthContextPush(pParse, &sContext, pTab->zName);
}
/* Begin generating code.
*/
v = sqliteGetVdbe(pParse);
if( v==0 ) goto update_cleanup;
sqliteBeginWriteOperation(pParse, 1, pTab->iDb);
/* If we are trying to update a view, construct that view into
** a temporary table.
*/
if( isView ){
Select *pView;
pView = sqliteSelectDup(pTab->pSelect);
sqliteSelect(pParse, pView, SRT_TempTable, iCur, 0, 0, 0);
sqliteSelectDelete(pView);
}
/* Begin the database scan
*/
pWInfo = sqliteWhereBegin(pParse, pTabList, pWhere, 1, 0);
if( pWInfo==0 ) goto update_cleanup;
/* Remember the index of every item to be updated.
*/
sqliteVdbeAddOp(v, OP_ListWrite, 0, 0);
/* End the database scan loop.
*/
sqliteWhereEnd(pWInfo);
/* Initialize the count of updated rows
*/
if( db->flags & SQLITE_CountRows && !pParse->trigStack ){
sqliteVdbeAddOp(v, OP_Integer, 0, 0);
}
if( row_triggers_exist ){
/* Create pseudo-tables for NEW and OLD
*/
sqliteVdbeAddOp(v, OP_OpenPseudo, oldIdx, 0);
sqliteVdbeAddOp(v, OP_OpenPseudo, newIdx, 0);
/* The top of the update loop for when there are triggers.
*/
sqliteVdbeAddOp(v, OP_ListRewind, 0, 0);
sqliteVdbeAddOp(v, OP_StackDepth, 0, 0);
sqliteVdbeAddOp(v, OP_MemStore, iStackDepth, 1);
loopStart = sqliteVdbeAddOp(v, OP_MemLoad, iStackDepth, 0);
sqliteVdbeAddOp(v, OP_StackReset, 0, 0);
jumpInst = sqliteVdbeAddOp(v, OP_ListRead, 0, 0);
sqliteVdbeAddOp(v, OP_Dup, 0, 0);
/* Open a cursor and make it point to the record that is
** being updated.
*/
sqliteVdbeAddOp(v, OP_Dup, 0, 0);
if( !isView ){
sqliteVdbeAddOp(v, OP_Integer, pTab->iDb, 0);
sqliteVdbeAddOp(v, OP_OpenRead, iCur, pTab->tnum);
}
sqliteVdbeAddOp(v, OP_MoveTo, iCur, 0);
/* Generate the OLD table
*/
sqliteVdbeAddOp(v, OP_Recno, iCur, 0);
sqliteVdbeAddOp(v, OP_RowData, iCur, 0);
sqliteVdbeAddOp(v, OP_PutIntKey, oldIdx, 0);
/* Generate the NEW table
*/
if( chngRecno ){
sqliteExprCode(pParse, pRecnoExpr);
}else{
sqliteVdbeAddOp(v, OP_Recno, iCur, 0);
}
for(i=0; i<pTab->nCol; i++){
if( i==pTab->iPKey ){
sqliteVdbeAddOp(v, OP_String, 0, 0);
continue;
}
j = aXRef[i];
if( j<0 ){
sqliteVdbeAddOp(v, OP_Column, iCur, i);
}else{
sqliteExprCode(pParse, pChanges->a[j].pExpr);
}
}
sqliteVdbeAddOp(v, OP_MakeRecord, pTab->nCol, 0);
sqliteVdbeAddOp(v, OP_PutIntKey, newIdx, 0);
if( !isView ){
sqliteVdbeAddOp(v, OP_Close, iCur, 0);
}
/* Fire the BEFORE and INSTEAD OF triggers
*/
if( sqliteCodeRowTrigger(pParse, TK_UPDATE, pChanges, TK_BEFORE, pTab,
newIdx, oldIdx, onError, loopStart) ){
goto update_cleanup;
}
}
if( !isView ){
/*
** Open every index that needs updating. Note that if any
** index could potentially invoke a REPLACE conflict resolution
** action, then we need to open all indices because we might need
** to be deleting some records.
*/
sqliteVdbeAddOp(v, OP_Integer, pTab->iDb, 0);
sqliteVdbeAddOp(v, OP_OpenWrite, iCur, pTab->tnum);
if( onError==OE_Replace ){
openAll = 1;
}else{
openAll = 0;
for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
if( pIdx->onError==OE_Replace ){
openAll = 1;
break;
}
}
}
for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
if( openAll || aIdxUsed[i] ){
sqliteVdbeAddOp(v, OP_Integer, pIdx->iDb, 0);
sqliteVdbeAddOp(v, OP_OpenWrite, iCur+i+1, pIdx->tnum);
assert( pParse->nTab>iCur+i+1 );
}
}
/* Loop over every record that needs updating. We have to load
** the old data for each record to be updated because some columns
** might not change and we will need to copy the old value.
** Also, the old data is needed to delete the old index entires.
** So make the cursor point at the old record.
*/
if( !row_triggers_exist ){
sqliteVdbeAddOp(v, OP_ListRewind, 0, 0);
jumpInst = loopStart = sqliteVdbeAddOp(v, OP_ListRead, 0, 0);
sqliteVdbeAddOp(v, OP_Dup, 0, 0);
}
sqliteVdbeAddOp(v, OP_NotExists, iCur, loopStart);
/* If the record number will change, push the record number as it
** will be after the update. (The old record number is currently
** on top of the stack.)
*/
if( chngRecno ){
sqliteExprCode(pParse, pRecnoExpr);
sqliteVdbeAddOp(v, OP_MustBeInt, 0, 0);
}
/* Compute new data for this record.
*/
for(i=0; i<pTab->nCol; i++){
if( i==pTab->iPKey ){
sqliteVdbeAddOp(v, OP_String, 0, 0);
continue;
}
j = aXRef[i];
if( j<0 ){
sqliteVdbeAddOp(v, OP_Column, iCur, i);
}else{
sqliteExprCode(pParse, pChanges->a[j].pExpr);
}
}
/* Do constraint checks
*/
sqliteGenerateConstraintChecks(pParse, pTab, iCur, aIdxUsed, chngRecno, 1,
onError, loopStart);
/* Delete the old indices for the current record.
*/
sqliteGenerateRowIndexDelete(db, v, pTab, iCur, aIdxUsed);
/* If changing the record number, delete the old record.
*/
if( chngRecno ){
sqliteVdbeAddOp(v, OP_Delete, iCur, 0);
}
/* Create the new index entries and the new record.
*/
sqliteCompleteInsertion(pParse, pTab, iCur, aIdxUsed, chngRecno, 1, -1);
}
/* Increment the row counter
*/
if( db->flags & SQLITE_CountRows && !pParse->trigStack){
sqliteVdbeAddOp(v, OP_AddImm, 1, 0);
}
/* If there are triggers, close all the cursors after each iteration
** through the loop. The fire the after triggers.
*/
if( row_triggers_exist ){
if( !isView ){
for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
if( openAll || aIdxUsed[i] )
sqliteVdbeAddOp(v, OP_Close, iCur+i+1, 0);
}
sqliteVdbeAddOp(v, OP_Close, iCur, 0);
pParse->nTab = iCur;
}
if( sqliteCodeRowTrigger(pParse, TK_UPDATE, pChanges, TK_AFTER, pTab,
newIdx, oldIdx, onError, loopStart) ){
goto update_cleanup;
}
}
/* Repeat the above with the next record to be updated, until
** all record selected by the WHERE clause have been updated.
*/
sqliteVdbeAddOp(v, OP_Goto, 0, loopStart);
sqliteVdbeChangeP2(v, jumpInst, sqliteVdbeCurrentAddr(v));
sqliteVdbeAddOp(v, OP_ListReset, 0, 0);
/* Close all tables if there were no FOR EACH ROW triggers */
if( !row_triggers_exist ){
for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
if( openAll || aIdxUsed[i] ){
sqliteVdbeAddOp(v, OP_Close, iCur+i+1, 0);
}
}
sqliteVdbeAddOp(v, OP_Close, iCur, 0);
pParse->nTab = iCur;
}else{
sqliteVdbeAddOp(v, OP_Close, newIdx, 0);
sqliteVdbeAddOp(v, OP_Close, oldIdx, 0);
}
sqliteVdbeAddOp(v, OP_SetCounts, 0, 0);
sqliteEndWriteOperation(pParse);
/*
** Return the number of rows that were changed.
*/
if( db->flags & SQLITE_CountRows && !pParse->trigStack ){
sqliteVdbeOp3(v, OP_ColumnName, 0, 1, "rows updated", P3_STATIC);
sqliteVdbeAddOp(v, OP_Callback, 1, 0);
}
update_cleanup:
sqliteAuthContextPop(&sContext);
sqliteFree(apIdx);
sqliteFree(aXRef);
sqliteSrcListDelete(pTabList);
sqliteExprListDelete(pChanges);
sqliteExprDelete(pWhere);
return;
}