1 files changed, 70 insertions, 19 deletions

diff --git a/sql/item_subselect.h b/sql/item_subselect.h
index c6963df2d53..79832116c67 100644
--- a/sql/item_subselect.h
+++ b/sql/item_subselect.h
@@ -24,42 +24,34 @@ struct st_select_lex;
 class JOIN;
 class select_subselect;
 
-/* simple (not depended of covered select ) subselect */
+/* base class for subselects */
 
 class Item_subselect :public Item
 {
 protected:
-  longlong int_value;
-  double real_value;
+  uint max_columns;
   my_bool assigned; /* value already assigned to subselect */
   my_bool executed; /* simple subselect is executed */
   my_bool optimized; /* simple subselect is optimized */
   my_bool error; /* error in query */
-  enum Item_result res_type;
 
   int exec();
-  void assign_null() 
+  virtual void assign_null() 
   {
     null_value= 1;
-    int_value= 0;
-    real_value= 0;
-    max_length= 4;
-    res_type= STRING_RESULT;
   }
 public:
   st_select_lex *select_lex;
   JOIN *join;
   select_subselect *result;
 
-  Item_subselect(THD *thd, st_select_lex *select_lex);
+  Item_subselect(THD *thd, st_select_lex *select_lex,
+		 select_subselect* result);
   Item_subselect(Item_subselect *item)
   {
     null_value= item->null_value;
-    int_value= item->int_value;
-    real_value= item->real_value;
-    max_length= item->max_length;
     decimals= item->decimals;
-    res_type= item->res_type;
+    max_columns= item->max_columns;
     assigned= item->assigned;
     executed= item->executed;
     select_lex= item->select_lex;
@@ -69,16 +61,75 @@ public:
     error= item->error;
   }
   enum Type type() const;
-  double val ();
-  longlong val_int ();
-  String *val_str (String *);
   bool is_null() { return null_value; }
   void make_field (Send_field *);
   bool fix_fields(THD *thd, TABLE_LIST *tables);
-  Item *new_item() { return new Item_subselect(this); }
-  enum Item_result result_type() const { return res_type; }
+  table_map used_tables() const;
 
   friend class select_subselect;
 };
 
 
+/* single value subselect */
+
+class Item_singleval_subselect :public Item_subselect
+{
+protected:
+  longlong int_value;
+  double real_value;
+  enum Item_result res_type;
+
+  virtual void assign_null() 
+  {
+    null_value= 1;
+    int_value= 0;
+    real_value= 0;
+    max_length= 4;
+    res_type= STRING_RESULT;
+  }
+public:
+  Item_singleval_subselect(THD *thd, st_select_lex *select_lex);
+  Item_singleval_subselect(Item_singleval_subselect *item):
+    Item_subselect(item)
+  {
+    int_value= item->int_value;
+    real_value= item->real_value;
+    max_length= item->max_length;
+    decimals= item->decimals;
+    res_type= item->res_type;
+  }
+  double val ();
+  longlong val_int ();
+  String *val_str (String *);
+  Item *new_item() { return new Item_singleval_subselect(this); }
+  enum Item_result result_type() const { return res_type; }
+
+  friend class select_singleval_subselect;
+};
+
+/* exists subselect */
+
+class Item_exists_subselect :public Item_subselect
+{
+protected:
+  longlong value;
+
+  virtual void assign_null() 
+  {
+    value= 0;
+  }
+public:
+  Item_exists_subselect(THD *thd, st_select_lex *select_lex);
+  Item_exists_subselect(Item_exists_subselect *item):
+    Item_subselect(item)
+  {
+    value= item->value;
+  }
+  Item *new_item() { return new Item_exists_subselect(this); }
+  enum Item_result result_type() const { return INT_RESULT;}
+  longlong val_int();
+  double val();
+  String *val_str(String*);
+
+  friend class select_exists_subselect;
+};