Implement subselects in target lists. Also, relax requirement that

subselects can only appear on the righthand side of a binary operator.
That's still true for quantified predicates like x = ANY (SELECT ...),
but a subselect that delivers a single result can now appear anywhere
in an expression.  This is implemented by changing EXPR_SUBLINK sublinks
to represent just the (SELECT ...) expression, without any 'left hand
side' or combining operator --- so they're now more like EXISTS_SUBLINK.
To handle the case of '(x, y, z) = (SELECT ...)', I added a new sublink
type MULTIEXPR_SUBLINK, which acts just like EXPR_SUBLINK used to.
But the grammar will only generate one for a multiple-left-hand-side
row expression.

1 files changed, 3 insertions, 9 deletions

diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index fce3800dc49..295d722b6a5 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.70 1999/10/07 04:23:06 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.71 1999/11/15 02:00:08 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -343,17 +343,11 @@ union_planner(Query *parse)
 		{
 			/* Expand SubLinks to SubPlans */
 			parse->havingQual = SS_process_sublinks(parse->havingQual);
-
-			/*
-			 * Check for ungrouped variables passed to subplans. (Probably
-			 * this should be done for the targetlist as well???  But we
-			 * should NOT do it for the WHERE qual, since WHERE is
-			 * evaluated pre-GROUP.)
-			 */
+			/* Check for ungrouped variables passed to subplans */
 			if (check_subplans_for_ungrouped_vars(parse->havingQual,
 												  parse->groupClause,
 												  parse->targetList))
-				elog(ERROR, "Sub-SELECT in HAVING clause must use only GROUPed attributes from outer SELECT");
+				elog(ERROR, "Sub-SELECT must use only GROUPed attributes from outer SELECT");
 		}
 	}