** This file contains C code routines that are called by the parser
** to handle SELECT statements in SQLite.
**
-** $Id: select.c,v 1.440 2008/06/30 18:12:28 danielk1977 Exp $
+** $Id: select.c,v 1.441 2008/07/01 14:09:14 danielk1977 Exp $
*/
#include "sqliteInt.h"
Column *aCol, *pCol;
sqlite3 *db = pParse->db;
+ if( sqlite3SelectResolve(pParse, pSelect, 0) ){
+ return 0;
+ }
+
while( pSelect->pPrior ) pSelect = pSelect->pPrior;
if( prepSelectStmt(pParse, pSelect) ){
return 0;
** not contain ORDER BY. (Ticket #2942) This used to not matter
** until we introduced the group_concat() function.
**
+** (17) The sub-query is not a compound select, or it is a UNION ALL
+** compound without an ORDER BY, LIMIT or OFFSET clause made up
+** entirely of non-aggregate queries, and
+** the parent query:
+**
+** * is not itself part of a compound select,
+** * is not an aggregate or DISTINCT query, and
+** * has no other tables or sub-selects in the FROM clause.
+**
+** The parent query may have WHERE, ORDER BY, LIMIT and OFFSET
+** clauses.
+**
** In this routine, the "p" parameter is a pointer to the outer query.
** The subquery is p->pSrc->a[iFrom]. isAgg is true if the outer query
** uses aggregates and subqueryIsAgg is true if the subquery uses aggregates.
int isAgg, /* True if outer SELECT uses aggregate functions */
int subqueryIsAgg /* True if the subquery uses aggregate functions */
){
+ Select *pParent;
Select *pSub; /* The inner query or "subquery" */
+ Select *pSub1; /* Pointer to the rightmost select in sub-query */
SrcList *pSrc; /* The FROM clause of the outer query */
SrcList *pSubSrc; /* The FROM clause of the subquery */
ExprList *pList; /* The result set of the outer query */
return 0;
}
- /* If we reach this point, it means flattening is permitted for the
- ** iFrom-th entry of the FROM clause in the outer query.
+ /* Restriction 17: If the sub-query is a compound SELECT, then it must
+ ** use only the UNION ALL operator. And none of the simple select queries
+ ** that make up the compound SELECT are allowed to be aggregate or distinct
+ ** queries.
+ */
+ if( pSub->pPrior ){
+ if( p->pPrior || isAgg || p->isDistinct || pSrc->nSrc!=1 ){
+ return 0;
+ }
+ for(pSub1=pSub; pSub1; pSub1=pSub1->pPrior){
+ if( pSub1->isAgg || pSub1->isDistinct
+ || (pSub1->pPrior && pSub1->op!=TK_ALL) ){
+ return 0;
+ }
+ }
+ }
+
+ /* If the sub-query is a compound SELECT statement, then it must be
+ ** a UNION ALL and the parent query must be of the form:
+ **
+ ** SELECT <expr-list> FROM (<sub-query>) <where-clause>
+ **
+ ** followed by any ORDER BY, LIMIT and/or OFFSET clauses. This block
+ ** creates N copies of the parent query without any ORDER BY, LIMIT or
+ ** OFFSET clauses and joins them to the left-hand-side of the original
+ ** using UNION ALL operators. In this case N is the number of simple
+ ** select statements in the compound sub-query.
*/
+ for(pSub=pSub->pPrior; pSub; pSub=pSub->pPrior){
+ Select *pNew;
+ ExprList *pOrderBy = p->pOrderBy;
+ Select *pPrior = p->pPrior;
+ p->pOrderBy = 0;
+ p->pSrc = 0;
+ p->pPrior = 0;
+ pNew = sqlite3SelectDup(db, p);
+ pNew->pPrior = pPrior;
+ p->pPrior = pNew;
+ p->pOrderBy = pOrderBy;
+ p->op = TK_ALL;
+ p->pSrc = pSrc;
+ p->pRightmost = 0;
+ pNew->pRightmost = 0;
+ }
- /* Move all of the FROM elements of the subquery into the
- ** the FROM clause of the outer query. Before doing this, remember
- ** the cursor number for the original outer query FROM element in
- ** iParent. The iParent cursor will never be used. Subsequent code
- ** will scan expressions looking for iParent references and replace
- ** those references with expressions that resolve to the subquery FROM
- ** elements we are now copying in.
+ /* If we reach this point, it means flattening is permitted for the
+ ** iFrom-th entry of the FROM clause in the outer query.
*/
+ pSub = pSub1 = pSubitem->pSelect;
iParent = pSubitem->iCursor;
- {
+ for(pParent=p; pParent; pParent=pParent->pPrior, pSub=pSub->pPrior){
int nSubSrc = pSubSrc->nSrc;
- int jointype = pSubitem->jointype;
-
- sqlite3DeleteTable(pSubitem->pTab);
- sqlite3_free(pSubitem->zDatabase);
- sqlite3_free(pSubitem->zName);
- sqlite3_free(pSubitem->zAlias);
- pSubitem->pTab = 0;
- pSubitem->zDatabase = 0;
- pSubitem->zName = 0;
- pSubitem->zAlias = 0;
- if( nSubSrc>1 ){
+ int jointype = 0;
+ pSubSrc = pSub->pSrc;
+ pSrc = pParent->pSrc;
+
+ /* Move all of the FROM elements of the subquery into the
+ ** the FROM clause of the outer query. Before doing this, remember
+ ** the cursor number for the original outer query FROM element in
+ ** iParent. The iParent cursor will never be used. Subsequent code
+ ** will scan expressions looking for iParent references and replace
+ ** those references with expressions that resolve to the subquery FROM
+ ** elements we are now copying in.
+ */
+ if( pSrc ){
+ pSubitem = &pSrc->a[iFrom];
+ nSubSrc = pSubSrc->nSrc;
+ jointype = pSubitem->jointype;
+ sqlite3DeleteTable(pSubitem->pTab);
+ sqlite3_free(pSubitem->zDatabase);
+ sqlite3_free(pSubitem->zName);
+ sqlite3_free(pSubitem->zAlias);
+ pSubitem->pTab = 0;
+ pSubitem->zDatabase = 0;
+ pSubitem->zName = 0;
+ pSubitem->zAlias = 0;
+ }
+ if( nSubSrc!=1 || !pSrc ){
int extra = nSubSrc - 1;
- for(i=1; i<nSubSrc; i++){
+ for(i=(pSrc?1:0); i<nSubSrc; i++){
pSrc = sqlite3SrcListAppend(db, pSrc, 0, 0);
if( pSrc==0 ){
- p->pSrc = 0;
+ pParent->pSrc = 0;
return 1;
}
}
- p->pSrc = pSrc;
+ pParent->pSrc = pSrc;
for(i=pSrc->nSrc-1; i-extra>=iFrom; i--){
pSrc->a[i] = pSrc->a[i-extra];
}
memset(&pSubSrc->a[i], 0, sizeof(pSubSrc->a[i]));
}
pSrc->a[iFrom].jointype = jointype;
- }
-
- /* Now begin substituting subquery result set expressions for
- ** references to the iParent in the outer query.
- **
- ** Example:
- **
- ** SELECT a+5, b*10 FROM (SELECT x*3 AS a, y+10 AS b FROM t1) WHERE a>b;
- ** \ \_____________ subquery __________/ /
- ** \_____________________ outer query ______________________________/
- **
- ** We look at every expression in the outer query and every place we see
- ** "a" we substitute "x*3" and every place we see "b" we substitute "y+10".
- */
- pList = p->pEList;
- for(i=0; i<pList->nExpr; i++){
- Expr *pExpr;
- if( pList->a[i].zName==0 && (pExpr = pList->a[i].pExpr)->span.z!=0 ){
- pList->a[i].zName =
- sqlite3DbStrNDup(db, (char*)pExpr->span.z, pExpr->span.n);
+
+ /* Now begin substituting subquery result set expressions for
+ ** references to the iParent in the outer query.
+ **
+ ** Example:
+ **
+ ** SELECT a+5, b*10 FROM (SELECT x*3 AS a, y+10 AS b FROM t1) WHERE a>b;
+ ** \ \_____________ subquery __________/ /
+ ** \_____________________ outer query ______________________________/
+ **
+ ** We look at every expression in the outer query and every place we see
+ ** "a" we substitute "x*3" and every place we see "b" we substitute "y+10".
+ */
+ pList = pParent->pEList;
+ for(i=0; i<pList->nExpr; i++){
+ Expr *pExpr;
+ if( pList->a[i].zName==0 && (pExpr = pList->a[i].pExpr)->span.z!=0 ){
+ pList->a[i].zName =
+ sqlite3DbStrNDup(db, (char*)pExpr->span.z, pExpr->span.n);
+ }
+ }
+ substExprList(db, pParent->pEList, iParent, pSub->pEList);
+ if( isAgg ){
+ substExprList(db, pParent->pGroupBy, iParent, pSub->pEList);
+ substExpr(db, pParent->pHaving, iParent, pSub->pEList);
+ }
+ if( pSub->pOrderBy ){
+ assert( pParent->pOrderBy==0 );
+ pParent->pOrderBy = pSub->pOrderBy;
+ pSub->pOrderBy = 0;
+ }else if( pParent->pOrderBy ){
+ substExprList(db, pParent->pOrderBy, iParent, pSub->pEList);
+ }
+ if( pSub->pWhere ){
+ pWhere = sqlite3ExprDup(db, pSub->pWhere);
+ }else{
+ pWhere = 0;
+ }
+ if( subqueryIsAgg ){
+ assert( pParent->pHaving==0 );
+ pParent->pHaving = pParent->pWhere;
+ pParent->pWhere = pWhere;
+ substExpr(db, pParent->pHaving, iParent, pSub->pEList);
+ pParent->pHaving = sqlite3ExprAnd(db, pParent->pHaving,
+ sqlite3ExprDup(db, pSub->pHaving));
+ assert( pParent->pGroupBy==0 );
+ pParent->pGroupBy = sqlite3ExprListDup(db, pSub->pGroupBy);
+ }else{
+ substExpr(db, pParent->pWhere, iParent, pSub->pEList);
+ pParent->pWhere = sqlite3ExprAnd(db, pParent->pWhere, pWhere);
+ }
+
+ /* The flattened query is distinct if either the inner or the
+ ** outer query is distinct.
+ */
+ pParent->isDistinct = pParent->isDistinct || pSub->isDistinct;
+
+ /*
+ ** SELECT ... FROM (SELECT ... LIMIT a OFFSET b) LIMIT x OFFSET y;
+ **
+ ** One is tempted to try to add a and b to combine the limits. But this
+ ** does not work if either limit is negative.
+ */
+ if( pSub->pLimit ){
+ pParent->pLimit = pSub->pLimit;
+ pSub->pLimit = 0;
}
- }
- substExprList(db, p->pEList, iParent, pSub->pEList);
- if( isAgg ){
- substExprList(db, p->pGroupBy, iParent, pSub->pEList);
- substExpr(db, p->pHaving, iParent, pSub->pEList);
- }
- if( pSub->pOrderBy ){
- assert( p->pOrderBy==0 );
- p->pOrderBy = pSub->pOrderBy;
- pSub->pOrderBy = 0;
- }else if( p->pOrderBy ){
- substExprList(db, p->pOrderBy, iParent, pSub->pEList);
- }
- if( pSub->pWhere ){
- pWhere = sqlite3ExprDup(db, pSub->pWhere);
- }else{
- pWhere = 0;
- }
- if( subqueryIsAgg ){
- assert( p->pHaving==0 );
- p->pHaving = p->pWhere;
- p->pWhere = pWhere;
- substExpr(db, p->pHaving, iParent, pSub->pEList);
- p->pHaving = sqlite3ExprAnd(db, p->pHaving,
- sqlite3ExprDup(db, pSub->pHaving));
- assert( p->pGroupBy==0 );
- p->pGroupBy = sqlite3ExprListDup(db, pSub->pGroupBy);
- }else{
- substExpr(db, p->pWhere, iParent, pSub->pEList);
- p->pWhere = sqlite3ExprAnd(db, p->pWhere, pWhere);
- }
-
- /* The flattened query is distinct if either the inner or the
- ** outer query is distinct.
- */
- p->isDistinct = p->isDistinct || pSub->isDistinct;
-
- /*
- ** SELECT ... FROM (SELECT ... LIMIT a OFFSET b) LIMIT x OFFSET y;
- **
- ** One is tempted to try to add a and b to combine the limits. But this
- ** does not work if either limit is negative.
- */
- if( pSub->pLimit ){
- p->pLimit = pSub->pLimit;
- pSub->pLimit = 0;
}
/* Finially, delete what is left of the subquery and return
** success.
*/
- sqlite3SelectDelete(pSub);
+ sqlite3SelectDelete(pSub1);
+
return 1;
}
#endif /* SQLITE_OMIT_VIEW */
p->pOrderBy = pOrderBy;
-#ifndef SQLITE_OMIT_COMPOUND_SELECT
- /* If there is are a sequence of queries, do the earlier ones first.
- */
- if( p->pPrior ){
- if( p->pRightmost==0 ){
- Select *pLoop, *pRight = 0;
- int cnt = 0;
- int mxSelect;
- for(pLoop=p; pLoop; pLoop=pLoop->pPrior, cnt++){
- pLoop->pRightmost = p;
- pLoop->pNext = pRight;
- pRight = pLoop;
- }
- mxSelect = db->aLimit[SQLITE_LIMIT_COMPOUND_SELECT];
- if( mxSelect && cnt>mxSelect ){
- sqlite3ErrorMsg(pParse, "too many terms in compound SELECT");
- return 1;
- }
- }
- return multiSelect(pParse, p, pDest, aff);
- }
-#endif
-
/* Make local copies of the parameters for this query.
*/
pTabList = p->pSrc;
/* Generate code for all sub-queries in the FROM clause
*/
#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
- for(i=0; i<pTabList->nSrc; i++){
+ for(i=0;
!p->pPrior && i<pTabList->nSrc; i++){
struct SrcList_item *pItem = &pTabList->a[i];
SelectDest dest;
Select *pSub = pItem->pSelect;
+ int isAggSub;
if( pSub==0 || pItem->isPopulated ) continue;
if( pItem->zName!=0 ){ /* An sql view */
pParse->nHeight += sqlite3SelectExprHeight(p);
/* Check to see if the subquery can be absorbed into the parent. */
- if( !pSub->pPrior && flattenSubquery(db, p, i, isAgg, pSub->isAgg) ){
- if( pSub->isAgg ){
+ isAggSub = pSub->isAgg;
+ if( flattenSubquery(db, p, i, isAgg, isAggSub) ){
+ if( isAggSub ){
p->isAgg = isAgg = 1;
}
i = -1;
pHaving = p->pHaving;
isDistinct = p->isDistinct;
+#ifndef SQLITE_OMIT_COMPOUND_SELECT
+ /* If there is are a sequence of queries, do the earlier ones first.
+ */
+ if( p->pPrior ){
+ if( p->pRightmost==0 ){
+ Select *pLoop, *pRight = 0;
+ int cnt = 0;
+ int mxSelect;
+ for(pLoop=p; pLoop; pLoop=pLoop->pPrior, cnt++){
+ pLoop->pRightmost = p;
+ pLoop->pNext = pRight;
+ pRight = pLoop;
+ }
+ mxSelect = db->aLimit[SQLITE_LIMIT_COMPOUND_SELECT];
+ if( mxSelect && cnt>mxSelect ){
+ sqlite3ErrorMsg(pParse, "too many terms in compound SELECT");
+ return 1;
+ }
+ }
+ return multiSelect(pParse, p, pDest, aff);
+ }
+#endif
+
/* If possible, rewrite the query to use GROUP BY instead of DISTINCT.
** GROUP BY may use an index, DISTINCT never does.
*/
projects / thirdparty / sqlite.git / commitdiff
