fixed bug in string & date types with group function in subselect

mysql-test/r/subselect.result

@@ -131,4 +131,20 @@ patient_uq	clinic_uq
 1	1
 1	2
 2	2
+drop table if exists t1,t2,t3;
+CREATE TABLE t3 (a varchar(20),b char(1) NOT NULL default '0');
+INSERT INTO t3 VALUES ('W','a'),('A','c'),('J','b');
+CREATE TABLE t2 (a varchar(20),b int NOT NULL default '0');
+INSERT INTO t2 VALUES ('W','1'),('A','3'),('J','2');
+CREATE TABLE t1 (a varchar(20),b date NOT NULL default '0000-00-00');
+INSERT INTO t1 VALUES ('W','1732-02-22'),('A','1735-10-30'),('J','1743-04-13');
+SELECT * FROM t1 WHERE b = (SELECT MIN(b) FROM t1);
+a	b
+W	1732-02-22
+SELECT * FROM t2 WHERE b = (SELECT MIN(b) FROM t2);
+a	b
+W	1
+SELECT * FROM t3 WHERE b = (SELECT MIN(b) FROM t3);
+a	b
+W	a
 drop table t1,t2,t3,t4,t5,attend,clinic;

mysql-test/t/subselect.test

@@ -53,4 +53,17 @@ insert into clinic values(1,"Oblastnaia bolnitsa"),(2,"Bolnitsa Krasnogo Kresta"
 insert into attend values (1,1),(1,2),(2,2),(1,3);
 select * from attend where exists (select * from clinic where uq = clinic_uq);
 
+# different tipes & group functions
+drop table if exists t1,t2,t3;
+
+CREATE TABLE t3 (a varchar(20),b char(1) NOT NULL default '0');
+INSERT INTO t3 VALUES ('W','a'),('A','c'),('J','b');
+CREATE TABLE t2 (a varchar(20),b int NOT NULL default '0');
+INSERT INTO t2 VALUES ('W','1'),('A','3'),('J','2');
+CREATE TABLE t1 (a varchar(20),b date NOT NULL default '0000-00-00');
+INSERT INTO t1 VALUES ('W','1732-02-22'),('A','1735-10-30'),('J','1743-04-13');
+SELECT * FROM t1 WHERE b = (SELECT MIN(b) FROM t1);
+SELECT * FROM t2 WHERE b = (SELECT MIN(b) FROM t2);
+SELECT * FROM t3 WHERE b = (SELECT MIN(b) FROM t3);
+
 drop table t1,t2,t3,t4,t5,attend,clinic;

sql/item_subselect.cc

@@ -82,7 +82,14 @@ bool Item_subselect::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
     my_message(ER_SUBSELECT_NO_1_COL, ER(ER_SUBSELECT_NO_1_COL), MYF(0));
     return 1;
   }
-  return engine->prepare();
+  int res= engine->prepare();
+  fix_length_and_dec();
+  return res;
+}
+
+void Item_subselect::fix_length_and_dec()
+{
+  engine->fix_length_and_dec();
 }
 
 inline table_map Item_subselect::used_tables() const
@@ -98,6 +105,12 @@ Item_singleval_subselect::Item_singleval_subselect(THD *thd,
   maybe_null= 1;
 }
 
+void Item_singleval_subselect::fix_length_and_dec()
+{
+  engine->fix_length_and_dec();
+  res_type= engine->type();
+}
+
 Item::Type Item_subselect::type() const 
 {
   return SUBSELECT_ITEM;
@@ -135,6 +148,12 @@ Item_exists_subselect::Item_exists_subselect(THD *thd,
   select_lex->select_limit= 1; // we need only 1 row to determinate existence
 }
 
+void Item_exists_subselect::fix_length_and_dec()
+{
+  max_length= 1;
+  
+}
+
 double Item_exists_subselect::val () 
 {
   if (engine->exec())
@@ -221,6 +240,32 @@ int subselect_union_engine::prepare()
   return unit->prepare(thd, result);
 }
 
+void subselect_single_select_engine::fix_length_and_dec()
+{
+  List_iterator_fast<Item> li(select_lex->item_list);
+  Item *sel_item= li++;
+  item->max_length= sel_item->max_length;
+  res_type= sel_item->result_type();
+  item->decimals= sel_item->decimals;
+}
+
+void subselect_union_engine::fix_length_and_dec()
+{
+  uint32 mlen= 0, len;
+  Item *sel_item= 0;
+  for(SELECT_LEX *sl= unit->first_select(); sl; sl= sl->next_select())
+  {
+    List_iterator_fast<Item> li(sl->item_list);
+    Item *s_item= li++;
+    if ((len= s_item->max_length))
+      mlen= len;
+    if (!sel_item)
+      sel_item= s_item;
+  }
+  item->max_length= mlen;
+  res_type= sel_item->result_type();
+  item->decimals= sel_item->decimals;
+}
 
 int subselect_single_select_engine::exec()
 {

sql/item_subselect.h

@@ -61,6 +61,7 @@ public:
   bool is_null() { return null_value; }
   void make_field (Send_field *);
   bool fix_fields(THD *thd, TABLE_LIST *tables, Item **ref);
+  virtual void fix_length_and_dec();
   table_map used_tables() const;
 
   friend class select_subselect;
@@ -100,7 +101,7 @@ public:
   String *val_str (String *);
   Item *new_item() { return new Item_singleval_subselect(this); }
   enum Item_result result_type() const { return res_type; }
-
+  void fix_length_and_dec();
   friend class select_singleval_subselect;
 };
 
@@ -128,7 +129,7 @@ public:
   longlong val_int();
   double val();
   String *val_str(String*);
-
+  void fix_length_and_dec();
   friend class select_exists_subselect;
 };
 
@@ -138,6 +139,7 @@ protected:
   select_subselect *result; /* results storage class */
   THD *thd; /* pointer to current THD */
   Item_subselect *item; /* item, that use this engine */
+  enum Item_result res_type; /* type of results */
 public:
   static void *operator new(size_t size)
   {
@@ -150,11 +152,15 @@ public:
     result= res;
     item= si;
     this->thd= thd;
+    res_type= STRING_RESULT;
   }
+
   virtual int prepare()= 0;
+  virtual void fix_length_and_dec()= 0;
   virtual int exec()= 0;
   virtual uint cols()= 0; /* return number of columnss in select */
   virtual bool depended()= 0; /* depended from outer select */
+  enum Item_result type() { return res_type; }
 };
 
 class subselect_single_select_engine: public subselect_engine
@@ -168,6 +174,7 @@ public:
 				 select_subselect *result,
 				 Item_subselect *item);
   virtual int prepare();
+  virtual void fix_length_and_dec();
   virtual int exec();
   virtual uint cols();
   virtual bool depended();
@@ -182,6 +189,7 @@ public:
 			 select_subselect *result,
 			 Item_subselect *item);
   virtual int prepare();
+  virtual void fix_length_and_dec();
   virtual int exec();
   virtual uint cols();
   virtual bool depended();

sql/sql_class.cc

@@ -838,12 +838,16 @@ bool select_singleval_subselect::send_data(List<Item> &items)
   if ((it->null_value= val_item->is_null()))
   {
     it->assign_null();
-  } else {
+  } 
+  else 
+  {
     it->max_length= val_item->max_length;
     it->decimals= val_item->decimals;
     it->binary= val_item->binary;
-    val_item->val_str(&it->str_value);
     it->int_value= val_item->val_int();
+    String *s= val_item->val_str(&it->str_value);
+    if (s != &it->str_value)
+      it->str_value.set(*s, 0, s->length());
     it->res_type= val_item->result_type();
   }
   it->assigned(1);