Fix for MIN/MAX with empty tables

MIN(key_column) could in some cases return NULL on a column with NULL and other values.
MIN(key_column) and MAX(key_column) could in some cases return wrong values when used in OUTER JOIN.

1 files changed, 2 insertions, 0 deletions

diff --git a/sql/item_sum.h b/sql/item_sum.h
index 2cf92343ebb..04f95dfd778 100644
--- a/sql/item_sum.h
+++ b/sql/item_sum.h
@@ -69,6 +69,7 @@ public:
   void make_field(Send_field *field);
   void print(String *str);
   void fix_num_length_and_dec();
+  void no_rows_in_result() { reset(); }
   virtual bool setup(THD *thd) {return 0;}
   unsigned int size_of() { return sizeof(*this);}  
 };
@@ -135,6 +136,7 @@ class Item_sum_count :public Item_sum_int
   bool const_item() const { return !used_table_cache; }
   enum Sumfunctype sum_func () const { return COUNT_FUNC; }
   void reset();
+  void no_rows_in_result() { count=0; }
   bool add();
   void make_const(longlong count_arg) { count=count_arg; used_table_cache=0; }
   longlong val_int();