Clumsy but working fix for bug #11973 "SELECT .. INTO var_name; in trigger

cause crash on update".

Let us update "thd" pointer in LEX, all its units and in LEX::result before
executing statement in trigger body, since triggers are associated with TABLE
object and because of this can be used in different threads.

2 files changed, 36 insertions, 0 deletions

diff --git a/mysql-test/r/trigger.result b/mysql-test/r/trigger.result
index 52bf307a686..99abfc6db96 100644
--- a/mysql-test/r/trigger.result
+++ b/mysql-test/r/trigger.result
@@ -635,3 +635,16 @@ show triggers;
 Trigger	Event	Table	Statement	Timing	Created	sql_mode
 t1_bi	INSERT	t1	 set new.a = '2004-01-00'	BEFORE	#	
 drop table t1;
+create table t1 (id int, data int, username varchar(16));
+insert into t1 (id, data) values (1, 0);
+create trigger t1_whoupdated before update on t1 for each row
+begin
+declare user varchar(32);
+declare i int;
+select user() into user;
+set NEW.username = user;
+select count(*) from ((select 1) union (select 2)) as d1 into i;
+end|
+update t1 set data = 1;
+update t1 set data = 2;
+drop table t1;
diff --git a/mysql-test/t/trigger.test b/mysql-test/t/trigger.test
index 7bf8b1a4e2b..3d5d3448a1b 100644
--- a/mysql-test/t/trigger.test
+++ b/mysql-test/t/trigger.test
@@ -642,3 +642,26 @@ show create table t1;
 --replace_column 6 #
 show triggers;
 drop table t1;
+
+# Test for bug #11973 "SELECT .. INTO var_name; in trigger cause
+#                      crash on update"
+create table t1 (id int, data int, username varchar(16));
+insert into t1 (id, data) values (1, 0);
+delimiter |;
+create trigger t1_whoupdated before update on t1 for each row
+begin
+  declare user varchar(32);
+  declare i int;
+  select user() into user;
+  set NEW.username = user;
+  select count(*) from ((select 1) union (select 2)) as d1 into i;
+end|
+delimiter ;|
+update t1 set data = 1;
+
+connect (addconroot, localhost, root,,);
+connection addconroot;
+update t1 set data = 2;
+
+connection default;
+drop table t1;