fixed bug with type of user variables (bug #551)

mysql-test/r/user_var.result:
  added tests for user variables comparing (bug #551)
mysql-test/t/user_var.test:
  added tests for user variables comparing (bug #551)
BitKeeper/etc/logging_ok:
  Logging to logging@openlogging.org accepted

BitKeeper/etc/logging_ok

@@ -35,5 +35,6 @@ serg@build.mysql2.com
 serg@serg.mysql.com
 serg@sergbook.mysql.com
 sinisa@rhols221.adsl.netsonic.fi
+vva@eagle.mysql.r18.ru
 walrus@mysql.com
 zak@balfor.local

mysql-test/r/user_var.result

@@ -14,3 +14,11 @@ table	type	possible_keys	key	key_len	ref	rows	Extra
 t1	index	NULL	i	4	NULL	3	where used; Using index
 table	type	possible_keys	key	key_len	ref	rows	Extra
 t1	ref	i	i	4	const	1	where used
+@a:=10	@b:=1	@a > @b	@a < @b
+10	1	1	0
+@a:="10"	@b:="1"	@a > @b	@a < @b
+10	1	1	0
+@a:=10	@b:=2	@a > @b	@a < @b
+10	2	1	0
+@a:="10"	@b:="2"	@a > @b	@a < @b
+10	2	0	1

mysql-test/t/user_var.test

@@ -17,3 +17,9 @@ explain select * from t1 where @vv1:=@vv1+1 and i=@vv1;
 explain select @vv1:=i from t1 where i=@vv1;
 explain select * from t1 where i=@vv1;
 drop table t1,t2;
+
+# Check types of variables
+select @a:=10,   @b:=1,   @a > @b, @a < @b;
+select @a:="10", @b:="1", @a > @b, @a < @b;
+select @a:=10,   @b:=2,   @a > @b, @a < @b;
+select @a:="10", @b:="2", @a > @b, @a < @b;

sql/item_func.cc

@@ -1676,6 +1676,7 @@ bool Item_func_set_user_var::fix_fields(THD *thd,TABLE_LIST *tables)
   if (Item_func::fix_fields(thd,tables) ||
       !(entry= get_variable(&thd->user_vars, name, 1)))
     return 1;
+  entry->type= cached_result_type;
   entry->update_query_id=thd->query_id;
   return 0;
 }