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Better resolution of ORDER BY terms in compound queries. Candidate

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solution for ticket #2822.  Needs more testing and documentation
before going final. (CVS 4602)

FossilOrigin-Name: 62a78d212c53a9cb1759d03134653a75f3a086b6
This commit is contained in:
drh
2007-12-08 21:10:20 +00:00
parent 9213d9e5fb
commit 4c77431448
5 changed files with 78 additions and 55 deletions
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103
src/select.c
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@@ -12,7 +12,7 @@
** This file contains C code routines that are called by the parser
** to handle SELECT statements in SQLite.
**
** $Id: select.c,v 1.363 2007/11/23 13:42:52 drh Exp $
** $Id: select.c,v 1.364 2007/12/08 21:10:20 drh Exp $
*/
#include "sqliteInt.h"
@@ -1412,6 +1412,15 @@ static int prepSelectStmt(Parse *pParse, Select *p){
return rc;
}
/*
** During the process of matching ORDER BY terms to columns of the
** result set, the Exprlist.a[].done flag can be set to one of the
** following values:
*/
#define ORDERBY_MATCH_NONE 0 /* No match found */
#define ORDERBY_MATCH_PARTIAL 1 /* A good match, but not perfect */
#define ORDERBY_MATCH_EXACT 2 /* An exact match seen */
#ifndef SQLITE_OMIT_COMPOUND_SELECT
/*
** This routine associates entries in an ORDER BY expression list with
@@ -1431,33 +1440,43 @@ static int matchOrderbyToColumn(
Select *pSelect, /* Match to result columns of this SELECT */
ExprList *pOrderBy, /* The ORDER BY values to match against columns */
int iTable, /* Insert this value in iTable */
int mustComplete /* If TRUE all ORDER BYs must match */
int rightMost /* TRUE for outermost recursive invocation */
){
int nErr = 0;
int i, j;
ExprList *pEList;
sqlite3 *db = pParse->db;
NameContext nc;
if( pSelect==0 || pOrderBy==0 ) return 1;
if( mustComplete ){
for(i=0; i<pOrderBy->nExpr; i++){ pOrderBy->a[i].done = 0; }
}
if( prepSelectStmt(pParse, pSelect) ){
return 1;
}
if( pSelect->pPrior ){
if( matchOrderbyToColumn(pParse, pSelect->pPrior, pOrderBy, iTable, 0) ){
return 1;
if( rightMost ){
assert( pSelect->pOrderBy==pOrderBy );
for(i=0; i<pOrderBy->nExpr; i++){
pOrderBy->a[i].done = ORDERBY_MATCH_NONE;
}
}
pEList = pSelect->pEList;
for(i=0; i<pOrderBy->nExpr; i++){
if( pSelect->pPrior
&& matchOrderbyToColumn(pParse, pSelect->pPrior, pOrderBy, iTable, 0) ){
return 1;
}
if( sqlite3SelectResolve(pParse, pSelect, 0) ){
return 1;
}
memset(&nc, 0, sizeof(nc));
nc.pParse = pParse;
nc.pSrcList = pSelect->pSrc;
nc.pEList = pEList = pSelect->pEList;
nc.allowAgg = 1;
for(i=0; nErr==0 && i<pOrderBy->nExpr; i++){
struct ExprList_item *pItem;
Expr *pE = pOrderBy->a[i].pExpr;
int iCol = -1;
char *zLabel;
int match = ORDERBY_MATCH_NONE;
Expr *pDup;
if( pOrderBy->a[i].done ) continue;
if( pOrderBy->a[i].done==ORDERBY_MATCH_EXACT ){
continue;
}
if( sqlite3ExprIsInteger(pE, &iCol) ){
if( iCol<=0 || iCol>pEList->nExpr ){
sqlite3ErrorMsg(pParse,
@@ -1466,34 +1485,38 @@ static int matchOrderbyToColumn(
nErr++;
break;
}
if( !mustComplete ) continue;
if( !rightMost ) continue;
iCol--;
match = ORDERBY_MATCH_EXACT;
}
if( iCol<0 && (zLabel = sqlite3NameFromToken(db, &pE->token))!=0 ){
for(j=0, pItem=pEList->a; j<pEList->nExpr; j++, pItem++){
char *zName;
int isMatch;
if( pItem->zName ){
zName = sqlite3DbStrDup(db, pItem->zName);
}else{
zName = sqlite3NameFromToken(db, &pItem->pExpr->token);
}
isMatch = zName && sqlite3StrICmp(zName, zLabel)==0;
sqlite3_free(zName);
if( isMatch ){
iCol = j;
break;
if( !match && pParse->nErr==0 && (pDup = sqlite3ExprDup(db, pE))!=0 ){
nc.nErr = 0;
assert( pParse->zErrMsg==0 );
if( sqlite3ExprResolveNames(&nc, pDup) ){
sqlite3ErrorClear(pParse);
}else{
for(j=0, pItem=pEList->a; j<pEList->nExpr; j++, pItem++){
if( sqlite3ExprCompare(pItem->pExpr, pDup) ){
iCol = j;
match = ORDERBY_MATCH_PARTIAL;
break;
}
}
}
sqlite3_free(zLabel);
sqlite3ExprDelete(pDup);
}
if( iCol>=0 ){
if( match ){
pE->op = TK_COLUMN;
pE->iColumn = iCol;
pE->iTable = iTable;
pE->iAgg = -1;
pOrderBy->a[i].done = 1;
}else if( mustComplete ){
if( pOrderBy->a[i].done!=ORDERBY_MATCH_NONE && pE->iColumn!=iCol ){
sqlite3ErrorMsg(pParse,
"ORDER BY term number %d is ambiguous", i+1);
nErr++;
}
pE->iColumn = iCol;
pOrderBy->a[i].done = match;
}else if( rightMost && pOrderBy->a[i].done==ORDERBY_MATCH_NONE ){
sqlite3ErrorMsg(pParse,
"ORDER BY term number %d does not match any result column", i+1);
nErr++;
@@ -2720,11 +2743,11 @@ int sqlite3SelectResolve(
sqlite3ExprResolveNames(&sNC, p->pHaving) ){
return SQLITE_ERROR;
}
if( p->pPrior==0 ){
if( processOrderGroupBy(&sNC, p->pOrderBy, "ORDER") ||
processOrderGroupBy(&sNC, pGroupBy, "GROUP") ){
return SQLITE_ERROR;
}
if( p->pPrior==0 && processOrderGroupBy(&sNC, p->pOrderBy, "ORDER") ){
return SQLITE_ERROR;
}
if( processOrderGroupBy(&sNC, pGroupBy, "GROUP") ){
return SQLITE_ERROR;
}
if( pParse->db->mallocFailed ){