Fixed 'Unknown error' when doing ORDER BY on reference table which

was used with NULL value on NOT NULL column. (Bug #479)

mysql-test/r/order_by.result

@@ -142,3 +142,7 @@ t3	eq_ref	PRIMARY	PRIMARY	2	t1.gid	1	where used
 table	type	possible_keys	key	key_len	ref	rows	Extra
 t1	ALL	NULL	NULL	NULL	NULL	6	Using temporary; Using filesort
 t3	eq_ref	PRIMARY	PRIMARY	2	t1.skr	1	where used
+t2_id	str
+112633	t2 112633
+112634	t2 112634
+t2_id	str

mysql-test/t/order_by.test

@@ -247,3 +247,26 @@ EXPLAIN SELECT t1.gid, t2.sid, t3.uid from t2, t1, t3 where t2.gid = t1.gid and
 EXPLAIN SELECT t1.gid, t3.uid from t1, t3 where t1.gid = t3.uid order by t3.skr,t1.gid;
 EXPLAIN SELECT t1.gid, t3.uid from t1, t3 where t1.skr = t3.uid order by t1.gid,t3.skr;
 drop table t1,t2,t3;
+
+#
+# Problem with lookup on NULL (Bug 479)
+#
+
+CREATE TABLE t1 (
+  t1_id int(10) unsigned NOT NULL default '0',
+  ref_id int(10) unsigned default NULL,
+  PRIMARY KEY  (t1_id)
+) TYPE=MyISAM;
+INSERT INTO t1 VALUES (2401,14590),(2425,NULL);
+CREATE TABLE t2 (
+  t2_id int(10) unsigned NOT NULL default '0',
+  ref_id int(10) unsigned NOT NULL default '0',
+  str varchar(20) default NULL,
+  PRIMARY KEY  (t2_id),
+  KEY ref_id (ref_id)
+) TYPE=MyISAM;
+INSERT INTO t2 VALUES (112633,14590,'t2 112633'),(112634,14590,'t2 112634'),(113166,14641,'t2 113166'),(113167,14641,'t2 113167'),(113168,14641,'t2 113168'),(113169,14641,'t2 113169'),(113170,14641,'t2 113170'),(113171,14641,'t2 113171'),(113172,14641,'t2 113172'),(113173,14641,'t2 113173'),(113174,14641,'t2 113174'),(113175,14641,'t2 113175'),(113436,14674,'t2 113436'),(113437,14674,'t2 113437'),(113486,14689,'t2 113486'),(113487,14689,'t2 113487'),(113488,14689,'t2 113488'),(113489,14689,'t2 113489'),(113504,14795,'t2 113504'),(115396,15024,'t2 115396'),(115397,15024,'t2 115397');
+SELECT t2_id, str FROM t1, t2 WHERE t1_id = 2401 AND t1.ref_id = t2.ref_id ORDER BY str, t2_id;
+# This one gave an error
+SELECT t2_id, str FROM t1, t2 WHERE t1_id = 2425 AND t1.ref_id = t2.ref_id ORDER BY str, t2_id;
+DROP TABLE t1,t2;

sql/sql_select.cc

@@ -5326,11 +5326,23 @@ create_sort_index(JOIN_TAB *tab,ORDER *order,ha_rows select_limit)
 	can use.
       */
       if (!(select->quick=get_ft_or_quick_select_for_ref(table, tab)))
-	goto err;
+      {
+	if (current_thd->fatal_error)
+	  goto err;				// End of memory
+	/*
+	  Impossible range (for example lookup on NULL on not null field)
+	  Create empty result set
+	*/
+	if (!(table->record_pointers= my_malloc(1, MYF(MY_WME))))
+	  goto err;
+	table->found_records= 0;
+	goto end;
+      }	
     }
   }
   table->found_records=filesort(&table,sortorder,length,
 				select, 0L, select_limit, &examined_rows);
+end:
   delete select;				// filesort did select
   tab->select=0;
   tab->select_cond=0;