fixed DISTINCT in subselect bug

small Item_ref fix


mysql-test/r/subselect.result:
  DISTINCT in subselect test
mysql-test/t/subselect.test:
  DISTINCT in subselect test
sql/sql_class.cc:
  fixed DISTINCT in subselect bug

mysql-test/r/subselect.result

@@ -198,4 +198,10 @@ EXPLAIN SELECT (SELECT DISTINCT date FROM searchconthardwarefr3 WHERE date='2002
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY								No tables used
 2	SUBSELECT	searchconthardwarefr3	index	NULL	PRIMARY	41	NULL	2	where used; Using index
+SELECT DISTINCT date FROM searchconthardwarefr3 WHERE date='2002-08-03';
+date
+2002-08-03
+SELECT (SELECT DISTINCT date FROM searchconthardwarefr3 WHERE date='2002-08-03');
+(SELECT DISTINCT date FROM searchconthardwarefr3 WHERE date='2002-08-03')
+2002-08-03
 drop table searchconthardwarefr3;

mysql-test/t/subselect.test

@@ -108,4 +108,6 @@ INSERT INTO searchconthardwarefr3 (topic,date,pseudo) VALUES
 ('43506','2002-10-02','joce'),('40143','2002-08-03','joce');
 EXPLAIN SELECT DISTINCT date FROM searchconthardwarefr3 WHERE date='2002-08-03';
 EXPLAIN SELECT (SELECT DISTINCT date FROM searchconthardwarefr3 WHERE date='2002-08-03');
+SELECT DISTINCT date FROM searchconthardwarefr3 WHERE date='2002-08-03';
+SELECT (SELECT DISTINCT date FROM searchconthardwarefr3 WHERE date='2002-08-03');
 drop table searchconthardwarefr3;
\ No newline at end of file

sql/item.h

@@ -71,6 +71,7 @@ class Item {
   virtual double  val_result() { return val(); }
   virtual longlong val_int_result() { return val_int(); }
   virtual String *str_result(String* tmp) { return val_str(tmp); }
+  virtual bool is_null_result() { return is_null(); }
   virtual table_map used_tables() const { return (table_map) 0L; }
   virtual bool basic_const_item() const { return 0; }
   virtual Item *new_item() { return 0; }	/* Only for const items */
@@ -124,6 +125,7 @@ class Item_field :public Item_ident
   double val_result();
   longlong val_int_result();
   String *str_result(String* tmp);
+  bool is_null_result() { return result_field->is_null(); }
   bool send(THD *thd, String *str_arg)
   {
     return result_field->send(thd,str_arg);
@@ -398,25 +400,25 @@ class Item_ref :public Item_ident
   double val()
   {
     double tmp=(*ref)->val_result();
-    null_value=(*ref)->null_value;
+    null_value=(*ref)->is_null_result();
     return tmp;
   }
   longlong val_int()
   {
     longlong tmp=(*ref)->val_int_result();
-    null_value=(*ref)->null_value;
+    null_value=(*ref)->is_null_result();
     return tmp;
   }
   String *val_str(String* tmp)
   {
     tmp=(*ref)->str_result(tmp);
-    null_value=(*ref)->null_value;
+    null_value=(*ref)->is_null_result();
     return tmp;
   }
   bool is_null()
   {
     (void) (*ref)->val_int_result();
-    return (*ref)->null_value;
+    return (*ref)->is_null_result();
   }
   bool get_date(TIME *ltime,bool fuzzydate)
   {  

sql/sql_class.cc

@@ -873,8 +873,8 @@ bool select_singleval_subselect::send_data(List<Item> &items)
     Following val() call have to be first, because function AVG() & STD()
     calculate value on it & determinate "is it NULL?".
   */
-  it->real_value= val_item->val();
-  if ((it->null_value= val_item->is_null()))
+  it->real_value= val_item->val_result();
+  if ((it->null_value= val_item->is_null_result()))
   {
     it->assign_null();
   } 
@@ -883,8 +883,8 @@ bool select_singleval_subselect::send_data(List<Item> &items)
     it->max_length= val_item->max_length;
     it->decimals= val_item->decimals;
     it->binary= val_item->binary;
-    it->int_value= val_item->val_int();
-    String *s= val_item->val_str(&it->string_value);
+    it->int_value= val_item->val_int_result();
+    String *s= val_item->str_result(&it->string_value);
     if (s != &it->string_value)
     {
       it->string_value.set(*s, 0, s->length());