drh
a2e00042a1
the WHERE, ORDER BY, GROUP BY, and/or HAVING clauses. (CVS 350) FossilOrigin-Name: 3684beab0f8a71ebdf453871bbde7a9ab1f65385
304 lines
9.4 KiB
C
304 lines
9.4 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: update.c,v 1.27 2002/01/22 03:13:42 drh 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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void sqliteUpdate(
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Parse *pParse, /* The parser context */
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Token *pTableName, /* 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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){
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int i, j; /* Loop counters */
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Table *pTab; /* The table to be updated */
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IdList *pTabList = 0; /* List containing only pTab */
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int end, addr; /* A couple of addresses in the generated code */
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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 base; /* Index of first available table cursor */
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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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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 openOp; /* Opcode used to open tables */
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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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if( pParse->nErr || sqlite_malloc_failed ) goto update_cleanup;
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db = pParse->db;
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/* Locate the table which we want to update. This table has to be
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** put in an IdList structure because some of the subroutines we
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** will be calling are designed to work with multiple tables and expect
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** an IdList* parameter instead of just a Table* parameter.
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*/
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pTabList = sqliteIdListAppend(0, pTableName);
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if( pTabList==0 ) goto update_cleanup;
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for(i=0; i<pTabList->nId; i++){
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pTabList->a[i].pTab = sqliteFindTable(db, pTabList->a[i].zName);
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if( pTabList->a[i].pTab==0 ){
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sqliteSetString(&pParse->zErrMsg, "no such table: ",
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pTabList->a[i].zName, 0);
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pParse->nErr++;
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goto update_cleanup;
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}
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if( pTabList->a[i].pTab->readOnly ){
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sqliteSetString(&pParse->zErrMsg, "table ", pTabList->a[i].zName,
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" may not be modified", 0);
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pParse->nErr++;
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goto update_cleanup;
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}
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}
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pTab = pTabList->a[0].pTab;
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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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/* Resolve the column names in all the expressions in both the
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** WHERE clause and in the new values. Also find the column index
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** for each column to be updated in the pChanges array.
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*/
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if( pWhere ){
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sqliteExprResolveInSelect(pParse, pWhere);
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}
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for(i=0; i<pChanges->nExpr; i++){
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sqliteExprResolveInSelect(pParse, pChanges->a[i].pExpr);
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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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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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sqliteSetString(&pParse->zErrMsg, "no such column: ",
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pChanges->a[i].zName, 0);
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pParse->nErr++;
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goto update_cleanup;
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}
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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=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
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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( nIdx>0 ){
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apIdx = sqliteMalloc( sizeof(Index*) * nIdx );
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if( apIdx==0 ) goto update_cleanup;
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}
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for(nIdx=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
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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 ) apIdx[nIdx++] = pIdx;
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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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if( (db->flags & SQLITE_InTrans)==0 ){
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sqliteVdbeAddOp(v, OP_Transaction, 0, 0);
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sqliteVdbeAddOp(v, OP_VerifyCookie, db->schema_cookie, 0);
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pParse->schemaVerified = 1;
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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);
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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 ){
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sqliteVdbeAddOp(v, OP_Integer, 0, 0);
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}
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/* Rewind the list of records that need to be updated and
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** open every index that needs updating.
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*/
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sqliteVdbeAddOp(v, OP_ListRewind, 0, 0);
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base = pParse->nTab;
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openOp = pTab->isTemp ? OP_OpenWrAux : OP_OpenWrite;
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sqliteVdbeAddOp(v, openOp, base, pTab->tnum);
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for(i=0; i<nIdx; i++){
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sqliteVdbeAddOp(v, openOp, base+i+1, apIdx[i]->tnum);
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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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end = sqliteVdbeMakeLabel(v);
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addr = sqliteVdbeAddOp(v, OP_ListRead, 0, end);
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sqliteVdbeAddOp(v, OP_Dup, 0, 0);
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sqliteVdbeAddOp(v, OP_MoveTo, base, 0);
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/* Delete the old indices for the current record.
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*/
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for(i=0; i<nIdx; i++){
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sqliteVdbeAddOp(v, OP_Dup, 0, 0);
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pIdx = apIdx[i];
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for(j=0; j<pIdx->nColumn; j++){
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int x = pIdx->aiColumn[j];
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if( x==pTab->iPKey ){
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sqliteVdbeAddOp(v, OP_Dup, j, 0);
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}else{
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sqliteVdbeAddOp(v, OP_Column, base, x);
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}
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}
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sqliteVdbeAddOp(v, OP_MakeIdxKey, pIdx->nColumn, 0);
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sqliteVdbeAddOp(v, OP_IdxDelete, base+i+1, 0);
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}
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/* If changing the record number, remove the old record number
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** from the top of the stack and replace it with the new one.
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*/
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if( chngRecno ){
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sqliteVdbeAddOp(v, OP_Pop, 1, 0);
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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_Dup, i, 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, base, 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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/* 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, 0, 0);
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}
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/* Insert new index entries that correspond to the new data
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*/
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for(i=0; i<nIdx; i++){
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sqliteVdbeAddOp(v, OP_Dup, pTab->nCol, 0); /* The KEY */
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pIdx = apIdx[i];
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for(j=0; j<pIdx->nColumn; j++){
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int idx = pIdx->aiColumn[j];
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if( idx==pTab->iPKey ){
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sqliteVdbeAddOp(v, OP_Dup, j, 0);
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}else{
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sqliteVdbeAddOp(v, OP_Dup, j+pTab->nCol-idx, 0);
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}
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}
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sqliteVdbeAddOp(v, OP_MakeIdxKey, pIdx->nColumn, 0);
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sqliteVdbeAddOp(v, OP_IdxPut, base+i+1, pIdx->isUnique);
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}
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/* Write the new data back into the database.
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*/
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sqliteVdbeAddOp(v, OP_MakeRecord, pTab->nCol, 0);
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sqliteVdbeAddOp(v, OP_Put, base, 0);
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/* Increment the count of rows affected by the update
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*/
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if( db->flags & SQLITE_CountRows ){
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sqliteVdbeAddOp(v, OP_AddImm, 1, 0);
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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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sqliteVdbeResolveLabel(v, end);
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sqliteVdbeAddOp(v, OP_ListReset, 0, 0);
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if( (db->flags & SQLITE_InTrans)==0 ){
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sqliteVdbeAddOp(v, OP_Commit, 0, 0);
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}
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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 ){
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sqliteVdbeAddOp(v, OP_ColumnCount, 1, 0);
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sqliteVdbeAddOp(v, OP_ColumnName, 0, 0);
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sqliteVdbeChangeP3(v, -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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sqliteFree(apIdx);
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sqliteFree(aXRef);
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sqliteIdListDelete(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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