SQLite

*/
static struct SrcList_item *isSelfJoinView(
  SrcList *pTabList,           /* Search for self-joins in this FROM clause */
  struct SrcList_item *pThis   /* Search for prior reference to this subquery */
){
  struct SrcList_item *pItem;
  for(pItem = pTabList->a; pItem<pThis; pItem++){
    Select *pS1;
    if( pItem->pSelect==0 ) continue;
    if( pItem->fg.viaCoroutine ) continue;
    if( pItem->zName==0 ) continue;
    if( sqlite3_stricmp(pItem->zDatabase, pThis->zDatabase)!=0 ) continue;
    if( sqlite3_stricmp(pItem->zName, pThis->zName)!=0 ) continue;
    pS1 = pItem->pSelect;
    if( pThis->pSelect->selId!=pS1->selId ){
      /* The query flattener left two different CTE tables with identical
      ** names in the same FROM clause. */
      continue;
    }
    if( sqlite3ExprCompare(0, pThis->pSelect->pWhere, pS1->pWhere, -1) ){


      /* The view was modified by some other optimization such as
      ** pushDownWhereTerms() */
      continue;
    }
    return pItem;
  }
  return 0;

#
do_execsql_test 20.1 {
  WITH c(i)AS(VALUES(9)UNION SELECT~i FROM c)SELECT max(5)>i fROM c;
} {0}
do_execsql_test 20.2 {
  WITH c(i)AS(VALUES(5)UNIoN SELECT 0)SELECT min(1)-i fROM c;
} {1}

# 2018-12-26
# Two different CTE tables with the same name appear in within a single FROM
# clause due to the query-flattener optimization.  make sure this does not cause
# problems.  This problem was discovered by Matt Denton.
#
do_execsql_test 21.1 {
   WITH RECURSIVE t21(a,b) AS (
    WITH t21(x) AS (VALUES(1))
    SELECT x, x FROM t21 ORDER BY 1
  )
  SELECT * FROM t21 AS tA, t21 AS tB
} {1 1 1 1}
do_execsql_test 21.2 {
  SELECT printf('',
     EXISTS (WITH RECURSIVE Table0 AS (WITH Table0 AS (SELECT DISTINCT 1)
                                       SELECT *, * FROM Table0 ORDER BY 1 DESC)
             SELECT * FROM Table0  NATURAL JOIN  Table0));
} {{}}

finish_test