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Further simplifications of the code for the LIMIT clause on an UPDATE or DELETE. Added a few test cases to wherelimit.test. (CVS 5797)

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FossilOrigin-Name: 282c6a46b25f4e4278fd4c8b0b1cde1de28d8f51
This commit is contained in:
shane
2008-10-10 18:25:45 +00:00
parent c30bfeee4e
commit 49ffdbf47e
6 changed files with 69 additions and 49 deletions
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61
src/delete.c
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@@ -12,7 +12,7 @@
** This file contains C code routines that are called by the parser
** in order to generate code for DELETE FROM statements.
**
** $Id: delete.c,v 1.180 2008/10/10 13:35:58 shane Exp $
** $Id: delete.c,v 1.181 2008/10/10 18:25:46 shane Exp $
*/
#include "sqliteInt.h"
@@ -126,24 +126,37 @@ void sqlite3MaterializeView(
** pLimitWhere (pInClause)
*/
Expr *sqlite3LimitWhere(
Parse *pParse, /* The parser context */
SrcList *pSrc, /* the FROM clause -- which tables to scan */
Expr *pWhere, /* The WHERE clause. May be null */
ExprList *pOrderBy, /* The ORDER BY clause. May be null */
Expr *pLimit, /* The LIMIT clause. May be null */
Expr *pOffset /* The OFFSET clause. May be null */
Parse *pParse, /* The parser context */
SrcList *pSrc, /* the FROM clause -- which tables to scan */
Expr *pWhere, /* The WHERE clause. May be null */
ExprList *pOrderBy, /* The ORDER BY clause. May be null */
Expr *pLimit, /* The LIMIT clause. May be null */
Expr *pOffset, /* The OFFSET clause. May be null */
char *zStmtType /* Either DELETE or UPDATE. For error messages. */
){
Expr *pWhereRowid = NULL;
Expr *pInClause = NULL;
Expr *pSelectRowid = NULL;
ExprList *pEList = NULL;
SrcList *pSelectSrc = NULL;
Select *pSelect = NULL;
Expr *pWhereRowid = NULL; /* WHERE rowid .. */
Expr *pInClause = NULL; /* WHERE rowid IN ( select ) */
Expr *pSelectRowid = NULL; /* SELECT rowid ... */
ExprList *pEList = NULL; /* Expression list contaning only pSelectRowid */
SrcList *pSelectSrc = NULL; /* SELECT rowid FROM x ... (dup of pSrc) */
Select *pSelect = NULL; /* Complete SELECT tree */
/* Check that there isn't an ORDER BY without a LIMIT clause.
*/
if( pOrderBy && (pLimit == 0) ) {
sqlite3ErrorMsg(pParse, "ORDER BY without LIMIT on %s", zStmtType);
pParse->parseError = 1;
goto limit_where_cleanup_2;
}
/* We only need to generate a select expression if there
** is a limit/offset term to enforce.
*/
if (!pLimit && !pOffset) return pWhere;
if( pLimit == 0 ) {
/* if pLimit is null, pOffset will always be null as well. */
assert( pOffset == 0 );
return pWhere;
}
/* Generate a select expression tree to enforce the limit/offset
** term for the DELETE or UPDATE statement. For example:
@@ -155,35 +168,43 @@ Expr *sqlite3LimitWhere(
*/
pSelectRowid = sqlite3Expr(pParse->db, TK_ROW, 0, 0, 0);
if( pSelectRowid == 0 ) return 0;
if( pSelectRowid == 0 ) goto limit_where_cleanup_2;
pEList = sqlite3ExprListAppend(pParse, 0, pSelectRowid, 0);
if( pEList == 0 ) return 0;
if( pEList == 0 ) goto limit_where_cleanup_2;
/* duplicate the FROM clause as it is needed by both the DELETE/UPDATE tree
** and the SELECT subtree. */
pSelectSrc = sqlite3SrcListDup(pParse->db, pSrc);
if( pSelectSrc == 0 ) {
sqlite3ExprListDelete(pParse->db, pEList);
return 0;
goto limit_where_cleanup_2;
}
/* generate the SELECT expression tree. */
pSelect = sqlite3SelectNew(pParse,pEList,pSelectSrc,pWhere,0,0,pOrderBy,0,pLimit,pOffset);
if( pSelect == 0 ) return 0;
/* now generate the new WHERE rowid IN clause for the DELETE/UDPATE */
pWhereRowid = sqlite3Expr(pParse->db, TK_ROW, 0, 0, 0);
if( pWhereRowid == 0 ) goto limit_where_cleanup;
if( pWhereRowid == 0 ) goto limit_where_cleanup_1;
pInClause = sqlite3PExpr(pParse, TK_IN, pWhereRowid, 0, 0);
if( pInClause == 0 ) goto limit_where_cleanup;
if( pInClause == 0 ) goto limit_where_cleanup_1;
pInClause->pSelect = pSelect;
sqlite3ExprSetHeight(pParse, pInClause);
return pInClause;
/* something went wrong. clean up anything allocated. */
limit_where_cleanup:
limit_where_cleanup_1:
sqlite3SelectDelete(pParse->db, pSelect);
return 0;
limit_where_cleanup_2:
sqlite3ExprDelete(pParse->db, pWhere);
sqlite3ExprListDelete(pParse->db, pOrderBy);
sqlite3ExprDelete(pParse->db, pLimit);
sqlite3ExprDelete(pParse->db, pOffset);
return 0;
}
#endif /* defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) && !defined(SQLITE_OMIT_SUBQUERY) */