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Do not allow an ON clause to references tables to its right if there is a

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RIGHT or LEFT join anywhere in the query.  Other RDBMSes prohibit this always,
but SQLite must allow ON clauses to reference tables to their right for legacy
compatibility, unless there is a RIGHT or LEFT join someplace in the query,
in which case there is no legacy to support.

FossilOrigin-Name: e615dbe02ca949252d1526ed5c48f8ce08159773ea2008ce666484379d0d9854
This commit is contained in:
drh
2022-06-20 17:04:44 +00:00
parent ae8776e092
commit d7480403bc
6 changed files with 46 additions and 27 deletions
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18
src/select.c
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@@ -424,11 +424,13 @@ void sqlite3SetJoinExpr(Expr *p, int iTable, u32 joinFlag){
}
}
/* Undo the work of sqlite3SetJoinExpr(). In the expression p, convert every
** term that is marked with EP_OuterON and w.iJoin==iTable into
** an ordinary term that omits the EP_OuterON mark.
/* Undo the work of sqlite3SetJoinExpr(). This is used when a LEFT JOIN
** is simplified into an ordinary JOIN, and when an ON expression is
** "pushed down" into the WHERE clause of a subquery.
**
** This happens when a LEFT JOIN is simplified into an ordinary JOIN.
** Convert every term that is marked with EP_OuterON and w.iJoin==iTable into
** an ordinary term that omits the EP_OuterON mark. Or if iTable<0, then
** just clear every EP_OuterON and EP_InnerON mark from the expression tree.
**
** If nullable is true, that means that Expr p might evaluate to NULL even
** if it is a reference to a NOT NULL column. This can happen, for example,
@@ -438,10 +440,9 @@ void sqlite3SetJoinExpr(Expr *p, int iTable, u32 joinFlag){
*/
static void unsetJoinExpr(Expr *p, int iTable, int nullable){
while( p ){
if( ExprHasProperty(p, EP_OuterON)
&& (iTable<0 || p->w.iJoin==iTable) ){
ExprClearProperty(p, EP_OuterON);
ExprSetProperty(p, EP_InnerON);
if( iTable<0 || (ExprHasProperty(p, EP_OuterON) && p->w.iJoin==iTable) ){
ExprClearProperty(p, EP_OuterON|EP_InnerON);
if( iTable>=0 ) ExprSetProperty(p, EP_InnerON);
}
if( p->op==TK_COLUMN && p->iTable==iTable && !nullable ){
ExprClearProperty(p, EP_CanBeNull);
@@ -6771,6 +6772,7 @@ int sqlite3Select(
SELECTTRACE(0x100,pParse,p,
("LEFT-JOIN simplifies to JOIN on term %d\n",i));
pItem->fg.jointype &= ~(JT_LEFT|JT_OUTER);
assert( pItem->iCursor>=0 );
unsetJoinExpr(p->pWhere, pItem->iCursor,
pTabList->a[0].fg.jointype & JT_LTORJ);
}