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Improved handling of USING and NATURAL JOIN in 3-way and higher joins.

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Ticket [3338b3fa19ac4ab]

FossilOrigin-Name: 551ce407bd77149865423511bd52eba2f404161a
This commit is contained in:
drh
2011-10-18 18:10:40 +00:00
parent 42495cd46f
commit e802c5da01
4 changed files with 118 additions and 30 deletions
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47
src/resolve.c
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@@ -98,6 +98,24 @@ static void resolveAlias(
sqlite3DbFree(db, pDup);
}
/*
** Return TRUE if the name zCol occurs anywhere in the USING clause.
**
** Return FALSE if the USING clause is NULL or if it does not contain
** zCol.
*/
static int nameInUsingClause(IdList *pUsing, const char *zCol){
if( pUsing ){
int k;
for(k=0; k<pUsing->nId; k++){
if( sqlite3StrICmp(pUsing->a[k].zName, zCol)==0 ) return 1;
}
}
return 0;
}
/*
** Given the name of a column of the form X.Y.Z or Y.Z or just Z, look up
** that name in the set of source tables in pSrcList and make the pExpr
@@ -189,7 +207,14 @@ static int lookupName(
}
for(j=0, pCol=pTab->aCol; j<pTab->nCol; j++, pCol++){
if( sqlite3StrICmp(pCol->zName, zCol)==0 ){
IdList *pUsing;
/* If there has been exactly one prior match and this match
** is for the right-hand table of a NATURAL JOIN or is in a
** USING clause, then skip this match.
*/
if( cnt==1 ){
if( pItem->jointype & JT_NATURAL ) continue;
if( nameInUsingClause(pItem->pUsing, zCol) ) continue;
}
cnt++;
pExpr->iTable = pItem->iCursor;
pExpr->pTab = pTab;
@@ -197,26 +222,6 @@ static int lookupName(
pSchema = pTab->pSchema;
/* Substitute the rowid (column -1) for the INTEGER PRIMARY KEY */
pExpr->iColumn = j==pTab->iPKey ? -1 : (i16)j;
if( i<pSrcList->nSrc-1 ){
if( pItem[1].jointype & JT_NATURAL ){
/* If this match occurred in the left table of a natural join,
** then skip the right table to avoid a duplicate match */
pItem++;
i++;
}else if( (pUsing = pItem[1].pUsing)!=0 ){
/* If this match occurs on a column that is in the USING clause
** of a join, skip the search of the right table of the join
** to avoid a duplicate match there. */
int k;
for(k=0; k<pUsing->nId; k++){
if( sqlite3StrICmp(pUsing->a[k].zName, zCol)==0 ){
pItem++;
i++;
break;
}
}
}
}
break;
}
}