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, 14 insertions, 15 deletions

diff --git a/sql/item_sum.h b/sql/item_sum.h
index bd946609745..8ceada278b8 100644
--- a/sql/item_sum.h
+++ b/sql/item_sum.h
@@ -62,7 +62,8 @@ public:
 
   enum Type type() const { return SUM_FUNC_ITEM; }
   virtual enum Sumfunctype sum_func () const=0;
-  virtual bool reset()=0;
+  inline bool reset() { clear(); return add(); };
+  virtual void clear()= 0;
   virtual bool add()=0;
   virtual void reset_field()=0;
   virtual void update_field(int offset)=0;
@@ -124,7 +125,7 @@ class Item_sum_sum :public Item_sum_num
   Item_sum_sum(THD *thd, Item_sum_sum &item) 
     :Item_sum_num(thd, item), sum(item.sum) {}
   enum Sumfunctype sum_func () const {return SUM_FUNC;}
-  bool reset();
+  void clear();
   bool add();
   double val();
   void reset_field();
@@ -151,7 +152,7 @@ class Item_sum_count :public Item_sum_int
   table_map used_tables() const { return used_table_cache; }
   bool const_item() const { return !used_table_cache; }
   enum Sumfunctype sum_func () const { return COUNT_FUNC; }
-  bool reset();
+  void clear();
   void no_rows_in_result() { count=0; }
   bool add();
   void make_const(longlong count_arg) { count=count_arg; used_table_cache=0; }
@@ -225,7 +226,7 @@ class Item_sum_count_distinct :public Item_sum_int
 
   table_map used_tables() const { return used_table_cache; }
   enum Sumfunctype sum_func () const { return COUNT_DISTINCT_FUNC; }
-  bool reset();
+  void clear();
   bool add();
   longlong val_int();
   void reset_field() { return ;}		// Never called
@@ -269,7 +270,7 @@ class Item_sum_avg :public Item_sum_num
   Item_sum_avg(THD *thd, Item_sum_avg &item)
     :Item_sum_num(thd, item), sum(item.sum), count(item.count) {}
   enum Sumfunctype sum_func () const {return AVG_FUNC;}
-  bool reset();
+  void clear();
   bool add();
   double val();
   void reset_field();
@@ -322,7 +323,7 @@ class Item_sum_variance : public Item_sum_num
     Item_sum_num(thd, item), sum(item.sum), sum_sqr(item.sum_sqr),
     count(item.count) {}
   enum Sumfunctype sum_func () const { return VARIANCE_FUNC; }
-  bool reset();
+  void clear();
   bool add();
   double val();
   void reset_field();
@@ -391,13 +392,12 @@ class Item_sum_hybrid :public Item_sum
   table_map used_tables() const { return used_table_cache; }
   bool const_item() const { return !used_table_cache; }
 
-  bool reset()
+  void clear()
   {
     sum=0.0;
     sum_int=0;
     value.length(0);
     null_value=1;
-    return add();
   }
   double val();
   longlong val_int();
@@ -451,7 +451,7 @@ class Item_sum_bit :public Item_sum_int
   Item_sum_bit(THD *thd, Item_sum_bit &item):
     Item_sum_int(thd, item), reset_bits(item.reset_bits), bits(item.bits) {}
   enum Sumfunctype sum_func () const {return SUM_BIT_FUNC;}
-  bool reset();
+  void clear();
   longlong val_int();
   void reset_field();
   void fix_length_and_dec()
@@ -509,8 +509,7 @@ public:
   enum Sumfunctype sum_func () const { return UDF_SUM_FUNC; }
   virtual bool have_field_update(void) const { return 0; }
 
-  bool reset() { return 0; }			/* TO BE FIXED */
-  bool clear();
+  void clear();
   bool add();
   void reset_field() {};
   void update_field(int offset_arg) {};
@@ -592,7 +591,7 @@ class Item_sum_udf_float :public Item_sum_num
   ~Item_sum_udf_float() {}
   enum Sumfunctype sum_func () const { return UDF_SUM_FUNC; }
   double val() { return 0.0; }
-  bool reset() { return 0; }
+  bool clear() {}
   bool add() { return 0; }  
   void update_field(int offset) {}
 };
@@ -609,7 +608,7 @@ public:
   enum Sumfunctype sum_func () const { return UDF_SUM_FUNC; }
   longlong val_int() { return 0; }
   double val() { return 0; }
-  bool reset() { return 0; }
+  void clear() {}
   bool add() { return 0; }  
   void update_field(int offset) {}
 };
@@ -629,7 +628,7 @@ public:
   enum Item_result result_type () const { return STRING_RESULT; }
   void fix_length_and_dec() { maybe_null=1; max_length=0; }
   enum Sumfunctype sum_func () const { return UDF_SUM_FUNC; }
-  bool reset() { return 0; }
+  void clear() {}
   bool add() { return 0; }  
   void update_field(int offset) {}
 };
@@ -715,7 +714,7 @@ class Item_func_group_concat : public Item_sum
   const char *func_name() const { return "group_concat"; }
   enum Type type() const { return SUM_FUNC_ITEM; }  
   virtual Item_result result_type () const { return STRING_RESULT; }
-  bool reset();
+  void clear();
   bool add();
   void reset_field();
   bool fix_fields(THD *, TABLE_LIST *, Item **);