diff options
Diffstat (limited to 'src')
-rw-r--r-- | src/select.c | 71 |
1 files changed, 43 insertions, 28 deletions
diff --git a/src/select.c b/src/select.c index a90877dc6..2568cf708 100644 --- a/src/select.c +++ b/src/select.c @@ -3160,34 +3160,43 @@ static int flattenSubquery( #endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */ /* -** Analyze the SELECT statement passed as an argument to see if it -** is a min() or max() query. Return WHERE_ORDERBY_MIN or WHERE_ORDERBY_MAX if -** it is, or 0 otherwise. At present, a query is considered to be -** a min()/max() query if: +** Based on the contents of the AggInfo structure indicated by the first +** argument, this function checks if the following are true: ** -** 1. There is a single object in the FROM clause. +** * the query contains just a single aggregate function, +** * the aggregate function is either min() or max(), and +** * the argument to the aggregate function is a column value. ** -** 2. There is a single expression in the result set, and it is -** either min(x) or max(x), where x is a column reference. +** If all of the above are true, then WHERE_ORDERBY_MIN or WHERE_ORDERBY_MAX +** is returned as appropriate. Also, *ppMinMax is set to point to the +** list of arguments passed to the aggregate before returning. +** +** Or, if the conditions above are not met, *ppMinMax is set to 0 and +** WHERE_ORDERBY_NORMAL is returned. */ -static u8 minMaxQuery(Select *p){ - Expr *pExpr; - ExprList *pEList = p->pEList; - - if( pEList->nExpr!=1 ) return WHERE_ORDERBY_NORMAL; - pExpr = pEList->a[0].pExpr; - if( pExpr->op!=TK_AGG_FUNCTION ) return 0; - if( NEVER(ExprHasProperty(pExpr, EP_xIsSelect)) ) return 0; - pEList = pExpr->x.pList; - if( pEList==0 || pEList->nExpr!=1 ) return 0; - if( pEList->a[0].pExpr->op!=TK_AGG_COLUMN ) return WHERE_ORDERBY_NORMAL; - assert( !ExprHasProperty(pExpr, EP_IntValue) ); - if( sqlite3StrICmp(pExpr->u.zToken,"min")==0 ){ - return WHERE_ORDERBY_MIN; - }else if( sqlite3StrICmp(pExpr->u.zToken,"max")==0 ){ - return WHERE_ORDERBY_MAX; +static u8 minMaxQuery(AggInfo *pAggInfo, ExprList **ppMinMax){ + int eRet = WHERE_ORDERBY_NORMAL; /* Return value */ + + *ppMinMax = 0; + if( pAggInfo->nFunc==1 ){ + Expr *pExpr = pAggInfo->aFunc[0].pExpr; /* Aggregate function */ + ExprList *pEList = pExpr->x.pList; /* Arguments to agg function */ + + assert( pExpr->op==TK_AGG_FUNCTION ); + if( pEList && pEList->nExpr==1 && pEList->a[0].pExpr->op==TK_AGG_COLUMN ){ + const char *zFunc = pExpr->u.zToken; + if( sqlite3StrICmp(zFunc, "min")==0 ){ + eRet = WHERE_ORDERBY_MIN; + *ppMinMax = pEList; + }else if( sqlite3StrICmp(zFunc, "max")==0 ){ + eRet = WHERE_ORDERBY_MAX; + *ppMinMax = pEList; + } + } } - return WHERE_ORDERBY_NORMAL; + + assert( *ppMinMax==0 || (*ppMinMax)->nExpr==1 ); + return eRet; } /* @@ -4527,11 +4536,17 @@ int sqlite3Select( ** Refer to code and comments in where.c for details. */ ExprList *pMinMax = 0; - u8 flag = minMaxQuery(p); + u8 flag = WHERE_ORDERBY_NORMAL; + + assert( p->pGroupBy==0 ); + assert( flag==0 ); + if( p->pHaving==0 ){ + flag = minMaxQuery(&sAggInfo, &pMinMax); + } + assert( flag==0 || (pMinMax!=0 && pMinMax->nExpr==1) ); + if( flag ){ - assert( !ExprHasProperty(p->pEList->a[0].pExpr, EP_xIsSelect) ); - assert( p->pEList->a[0].pExpr->x.pList->nExpr==1 ); - pMinMax = sqlite3ExprListDup(db, p->pEList->a[0].pExpr->x.pList,0); + pMinMax = sqlite3ExprListDup(db, pMinMax, 0); pDel = pMinMax; if( pMinMax && !db->mallocFailed ){ pMinMax->a[0].sortOrder = flag!=WHERE_ORDERBY_MIN ?1:0; |