I started adding the Having Clause and it works quite fine for

sequential scans! (I think it will also work with hash, index, etc
but I did not check it out! I made some High level changes which
should work for all access methods, but maybe I'm wrong. Please
let me know.)

Now it is possible to make queries like:

select s.sname, max(p.pid), min(p.pid) from part p, supplier s
where s.sid=p.sid group by s.sname having max(pid)=6 and min(pid)=1
or avg(pid)=4;

Having does not work yet for queries that contain a subselect
statement in the Having clause, I'll try to fix this in the next
days.

If there are some bugs, please let me know, I'll start to read the
mailinglists now!

Now here is the patch against the original 6.3 version (no snapshot!!):

Stefan

4 files changed, 11 insertions, 7 deletions

diff --git a/src/backend/parser/analyze.c b/src/backend/parser/analyze.c
index 64ec5fa37d9..6dfdd8c26fe 100644
--- a/src/backend/parser/analyze.c
+++ b/src/backend/parser/analyze.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/parser/analyze.c,v 1.71 1998/02/26 04:33:26 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/parser/analyze.c,v 1.72 1998/03/30 16:36:23 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -781,6 +781,10 @@ transformSelectStmt(ParseState *pstate, SelectStmt *stmt)
 	qry->targetList = transformTargetList(pstate, stmt->targetList);
 
 	qry->qual = transformWhereClause(pstate, stmt->whereClause);
+
+        /***S*H***/
+	qry->havingQual = transformWhereClause(pstate, stmt->havingClause);
+
 	qry->hasSubLinks = pstate->p_hasSubLinks;
 
 	qry->sortClause = transformSortClause(pstate,
diff --git a/src/backend/parser/gram.c b/src/backend/parser/gram.c
index 9c4cca1a40f..298852387dd 100644
--- a/src/backend/parser/gram.c
+++ b/src/backend/parser/gram.c
@@ -216,7 +216,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/parser/Attic/gram.c,v 2.4 1998/03/18 16:50:15 thomas Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/parser/Attic/gram.c,v 2.5 1998/03/30 16:36:32 momjian Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -6700,7 +6700,7 @@ case 463:
 case 464:
 #line 2529 "gram.y"
 {
-					elog(NOTICE, "HAVING not yet supported; ignore clause");
+					/***S*H***/ /* elog(NOTICE, "HAVING not yet supported; ignore clause");*/
 					yyval.node = yyvsp[0].node;
 				;
     break;}
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index e9808c91027..71812de58b4 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.7 1998/03/18 16:50:19 thomas Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.8 1998/03/30 16:36:35 momjian Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -2527,7 +2527,7 @@ groupby:  ColId
 
 having_clause:  HAVING a_expr
 				{
-					elog(NOTICE, "HAVING not yet supported; ignore clause");
+					/***S*H***/ /* elog(NOTICE, "HAVING not yet supported; ignore clause");*/
 					$$ = $2;
 				}
 		| /*EMPTY*/								{ $$ = NULL; }
diff --git a/src/backend/parser/parse_agg.c b/src/backend/parser/parse_agg.c
index e7a88101960..083d4ee15df 100644
--- a/src/backend/parser/parse_agg.c
+++ b/src/backend/parser/parse_agg.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_agg.c,v 1.9 1998/02/26 04:33:28 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_agg.c,v 1.10 1998/03/30 16:36:36 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -331,7 +331,7 @@ ParseAgg(ParseState *pstate, char *aggname, Oid basetype,
 	aggreg->target = lfirst(target);
 	if (usenulls)
 		aggreg->usenulls = true;
-
+	
 	pstate->p_hasAggs = true;
 
 	return aggreg;