fixed subselect null test

fixed method definition (overloading instead of redefinition)
fixed time expression type definition


mysql-test/r/subselect.result:
  test of subselect null test
mysql-test/t/subselect.test:
  test of subselect null test
sql/item.h:
  fixed method definition (overloading instead of redefinition)
sql/item_subselect.h:
  fixed subselect null test
sql/item_timefunc.cc:
  fixed time expression type definition

1 files changed, 5 insertions, 1 deletions

diff --git a/sql/item_subselect.h b/sql/item_subselect.h
index 7e46af09e2a..0e6f939803d 100644
--- a/sql/item_subselect.h
+++ b/sql/item_subselect.h
@@ -75,7 +75,11 @@ public:
   bool assigned() { return value_assigned; }
   void assigned(bool a) { value_assigned= a; }
   enum Type type() const;
-  bool is_null() { return null_value; }
+  bool is_null()
+  {
+    val_int();
+    return null_value;
+  }
   bool fix_fields(THD *thd, TABLE_LIST *tables, Item **ref);
   virtual void fix_length_and_dec();
   table_map used_tables() const;