reset() split in 2 function clear() & add()

aggregate function reinitialization (if no rows was found) made with help of clear()
(fixed BUG#860)


mysql-test/r/subselect.result:
  test for BUG#860
mysql-test/t/subselect.test:
  test for BUG#860
sql/item_sum.cc:
  reset() replaced with clear()
sql/item_sum.h:
  reset() replaced with clear()
  (reset now is just composition of clear() and add())
sql/item_uniq.h:
  reset() replaced with clear()
sql/sql_select.cc:
  removed NULL value assigment, now it will be done by clear() call
  function for clearing if there was not found any row in group
sql/sql_select.h:
  function for clearing if there was not found any row in group

1 files changed, 1 insertions, 1 deletions

diff --git a/sql/item_uniq.h b/sql/item_uniq.h
index f2c64c4bde9..e41397dac44 100644
--- a/sql/item_uniq.h
+++ b/sql/item_uniq.h
@@ -41,7 +41,7 @@ public:
     :Item_sum_num(thd, item) {}
   double val() { return 0.0; }  
   enum Sumfunctype sum_func () const {return UNIQUE_USERS_FUNC;}
-  bool reset() { return 0;}
+  void clear() {}
   bool add() { return 0; }
   void reset_field() {}
   void update_field(int offset) {}