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Improve the error messages used to report illegal recursive cte references.

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FossilOrigin-Name: 54eee9fe99290e59469bd3e1a66bb749887d37ee
This commit is contained in:
dan
2014-01-16 21:02:02 +00:00
parent eae73fbfb9
commit f2655fe8b6
6 changed files with 95 additions and 57 deletions
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66
src/select.c
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@@ -3533,44 +3533,6 @@ void sqlite3WithPush(Parse *pParse, With *pWith){
}
}
/*
** If argument pCte is not NULL, check if it is already a part of the
** stack of CTEs stored by the parser. If so, this indicates an illegal
** recursive reference in a CTE, set of mutually recursive CTEs. Store
** an error in the parser and return SQLITE_ERROR if this is the case.
**
** Otherwise, if pCte is not already part of the stack of CTEs stored
** in the parser, push it onto the stop of that stack.
*/
static int ctePush(Parse *pParse, struct Cte *pCte){
if( pCte ){
struct Cte *p;
for(p=pParse->pCte; p; p=p->pOuterCte){
if( p==pCte ){
sqlite3ErrorMsg(
pParse, "illegal recursive defininition in cte: %s", pCte->zName
);
return SQLITE_ERROR;
}
}
pCte->pOuterCte = pParse->pCte;
pParse->pCte = pCte;
}
return SQLITE_OK;
}
/*
** If argument pCte is not NULL, it must be a pointer to the CTE currently
** on top of the stack of CTEs stored in the parser. Remove it from that
** stack.
*/
static void ctePop(Parse *pParse, struct Cte *pCte){
if( pCte ){
assert( pParse->pCte==pCte );
pParse->pCte = pCte->pOuterCte;
}
}
/*
** This function checks if argument pFrom refers to a CTE declared by
** a WITH clause on the stack currently maintained by the parser. And,
@@ -3602,6 +3564,16 @@ static int withExpand(
ExprList *pEList;
Select *pSel;
Select *pLeft; /* Left-most SELECT statement */
int bMayRecursive; /* True if compound joined by UNION [ALL] */
/* If pCte->zErr is non-NULL at this point, then this is an illegal
** recursive reference to CTE pCte. Leave an error in pParse and return
** early. If pCte->zErr is NULL, then this is not a recursive reference.
** In this case, proceed. */
if( pCte->zErr ){
sqlite3ErrorMsg(pParse, pCte->zErr, pCte->zName);
return WRC_Abort;
}
pFrom->pTab = pTab = sqlite3DbMallocZero(db, sizeof(Table));
if( pTab==0 ) return WRC_Abort;
@@ -3616,7 +3588,8 @@ static int withExpand(
/* Check if this is a recursive CTE. */
pSel = pFrom->pSelect;
if( pSel->op==TK_ALL || pSel->op==TK_UNION ){
bMayRecursive = ( pSel->op==TK_ALL || pSel->op==TK_UNION );
if( bMayRecursive ){
int i;
SrcList *pSrc = pFrom->pSelect->pSrc;
for(i=0; i<pSrc->nSrc; i++){
@@ -3642,8 +3615,8 @@ static int withExpand(
}
assert( pTab->nRef==1 || ((pSel->selFlags&SF_Recursive) && pTab->nRef==2 ));
if( ctePush(pParse, pCte) ) return WRC_Abort;
sqlite3WalkSelect(pWalker, pTab->nRef==2 ? pSel->pPrior : pSel);
pCte->zErr = "circular reference to cte: %s";
sqlite3WalkSelect(pWalker, bMayRecursive ? pSel->pPrior : pSel);
for(pLeft=pSel; pLeft->pPrior; pLeft=pLeft->pPrior);
pEList = pLeft->pEList;
@@ -3658,8 +3631,15 @@ static int withExpand(
}
selectColumnsFromExprList(pParse, pEList, &pTab->nCol, &pTab->aCol);
if( pSel->selFlags & SF_Recursive ) sqlite3WalkSelect(pWalker, pSel);
ctePop(pParse, pCte);
if( bMayRecursive ){
if( pSel->selFlags & SF_Recursive ){
pCte->zErr = "multiple recursive references in cte: %s";
}else{
pCte->zErr = "recursive reference may not appear in sub-query: %s";
}
sqlite3WalkSelect(pWalker, pSel);
}
pCte->zErr = 0;
}
return SQLITE_OK;