multi_update.result:

  Test case for a #2996 bug fix
multi_update.test:
  test case for a #2996 bug fix
sql_select.cc:
  Fix for a bug #2996 involving multi-table updates over the const tables

mysql-test/r/multi_update.result

@@ -386,3 +386,17 @@ SELECT * from t2;
 a
 1
 DROP TABLE t1,t2;
+create table `t1` (   `p_id` int(10) unsigned NOT NULL auto_increment,   `p_code` varchar(20) NOT NULL default '',   `p_created` datetime NOT NULL default '0000-00-00 00:00:00',   `p_active` tinyint(1) unsigned NOT NULL default '1',   PRIMARY KEY  (`p_id`) );
+create table  `t2` (   `c2_id` int(10) unsigned  NULL auto_increment,   `c2_p_id` int(10) unsigned NOT NULL default '0',   `c2_note` text NOT NULL,   `c2_created` datetime NOT NULL default '0000-00-00 00:00:00',   `c2_active` tinyint(1) unsigned NOT NULL default '1',   PRIMARY KEY  (`c2_id`),   KEY `c2_p_id` (`c2_p_id`) );
+insert into t1 values (0,'A01-Comp',now(),1);
+insert into t1 values (0,'B01-Comp',now(),1);
+insert into t2 values (0,1,'A Note',now(),1);
+update t1 left join t2 on p_id = c2_p_id set c2_note = 'asdf-1' where p_id = 2;
+select * from t1;
+p_id	p_code	p_created	p_active
+1	A01-Comp	2004-03-11 23:21:29	1
+2	B01-Comp	2004-03-11 23:21:29	1
+select * from t2;
+c2_id	c2_p_id	c2_note	c2_created	c2_active
+1	1	A Note	2004-03-11 23:21:29	1
+drop table t1, t2;

mysql-test/t/multi_update.test

@@ -325,3 +325,17 @@ DELETE t2 FROM t1 AS t2, t2 AS t1 where t1.a=t2.a and t1.a=2;
 SELECT * from t1;
 SELECT * from t2;
 DROP TABLE t1,t2;
+
+#
+# Test update with const tables
+#
+
+create table `t1` (   `p_id` int(10) unsigned NOT NULL auto_increment,   `p_code` varchar(20) NOT NULL default '',   `p_created` datetime NOT NULL default '0000-00-00 00:00:00',   `p_active` tinyint(1) unsigned NOT NULL default '1',   PRIMARY KEY  (`p_id`) );
+create table  `t2` (   `c2_id` int(10) unsigned  NULL auto_increment,   `c2_p_id` int(10) unsigned NOT NULL default '0',   `c2_note` text NOT NULL,   `c2_created` datetime NOT NULL default '0000-00-00 00:00:00',   `c2_active` tinyint(1) unsigned NOT NULL default '1',   PRIMARY KEY  (`c2_id`),   KEY `c2_p_id` (`c2_p_id`) );
+insert into t1 values (0,'A01-Comp',now(),1);
+insert into t1 values (0,'B01-Comp',now(),1);
+insert into t2 values (0,1,'A Note',now(),1);
+update t1 left join t2 on p_id = c2_p_id set c2_note = 'asdf-1' where p_id = 2; 
+select * from t1;
+select * from t2;
+drop table t1, t2;

sql/sql_select.cc

@@ -4897,7 +4897,7 @@ join_read_const_table(JOIN_TAB *tab, POSITION *pos)
   if (tab->on_expr && !table->null_row)
   {
     if ((table->null_row= test(tab->on_expr->val_int() == 0)))
-      empty_record(table);
+      mark_as_null_row(table);  
   }
   if (!table->null_row)
     table->maybe_null=0;