Merge macbook.gmz:/Users/kgeorge/mysql/work/B11032-4.1-opt

into  macbook.gmz:/Users/kgeorge/mysql/work/B11032-5.0-opt

mysql-test/r/subselect.result

@@ -3017,6 +3017,23 @@ a	a IN (SELECT a FROM t1)
 2	NULL
 3	1
 DROP TABLE t1,t2;
+CREATE TABLE t1 (a DATETIME);
+INSERT INTO t1 VALUES ('1998-09-23'), ('2003-03-25');
+CREATE TABLE t2 AS SELECT 
+(SELECT a FROM t1 WHERE a < '2000-01-01') AS sub_a 
+FROM t1 WHERE a > '2000-01-01';
+SHOW CREATE TABLE t2;
+Table	Create Table
+t2	CREATE TABLE `t2` (
+  `sub_a` datetime default NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+CREATE TABLE t3 AS (SELECT a FROM t1 WHERE a < '2000-01-01') UNION (SELECT a FROM t1 WHERE a > '2000-01-01');
+SHOW CREATE TABLE t3;
+Table	Create Table
+t3	CREATE TABLE `t3` (
+  `a` datetime default NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+DROP TABLE t1,t2,t3;
 create table t1 (df decimal(5,1));
 insert into t1 values(1.1);
 insert into t1 values(2.2);

mysql-test/t/subselect.test

@@ -1972,6 +1972,22 @@ SELECT a, a IN (SELECT a FROM t1) FROM t2;
 
 DROP TABLE t1,t2;
 
+#
+# Bug #11302: getObject() returns a String for a sub-query of type datetime
+#
+CREATE TABLE t1 (a DATETIME);
+INSERT INTO t1 VALUES ('1998-09-23'), ('2003-03-25');
+
+CREATE TABLE t2 AS SELECT 
+  (SELECT a FROM t1 WHERE a < '2000-01-01') AS sub_a 
+   FROM t1 WHERE a > '2000-01-01';
+SHOW CREATE TABLE t2;
+
+CREATE TABLE t3 AS (SELECT a FROM t1 WHERE a < '2000-01-01') UNION (SELECT a FROM t1 WHERE a > '2000-01-01'); 
+SHOW CREATE TABLE t3;
+
+DROP TABLE t1,t2,t3;
+
 # End of 4.1 tests
 
 #

sql/item_subselect.cc

@@ -391,6 +391,15 @@ enum Item_result Item_singlerow_subselect::result_type() const
   return engine->type();
 }
 
+/* 
+ Don't rely on the result type to calculate field type. 
+ Ask the engine instead.
+*/
+enum_field_types Item_singlerow_subselect::field_type() const
+{
+  return engine->field_type();
+}
+
 void Item_singlerow_subselect::fix_length_and_dec()
 {
   if ((max_columns= engine->cols()) == 1)
@@ -1613,32 +1622,36 @@ bool subselect_single_select_engine::no_rows()
 }
 
 
-static Item_result set_row(List<Item> &item_list, Item *item,
-			   Item_cache **row, bool *maybe_null)
+/* 
+ makes storage for the output values for the subquery and calcuates 
+ their data and column types and their nullability.
+*/ 
+void subselect_engine::set_row(List<Item> &item_list, Item_cache **row)
 {
-  Item_result res_type= STRING_RESULT;
   Item *sel_item;
   List_iterator_fast<Item> li(item_list);
+  res_type= STRING_RESULT;
+  res_field_type= FIELD_TYPE_VAR_STRING;
   for (uint i= 0; (sel_item= li++); i++)
   {
     item->max_length= sel_item->max_length;
     res_type= sel_item->result_type();
+    res_field_type= sel_item->field_type();
     item->decimals= sel_item->decimals;
     item->unsigned_flag= sel_item->unsigned_flag;
-    *maybe_null= sel_item->maybe_null;
+    maybe_null= sel_item->maybe_null;
     if (!(row[i]= Item_cache::get_cache(res_type)))
-      return STRING_RESULT; // we should return something
+      return;
     row[i]->setup(sel_item);
   }
   if (item_list.elements > 1)
     res_type= ROW_RESULT;
-  return res_type;
 }
 
 void subselect_single_select_engine::fix_length_and_dec(Item_cache **row)
 {
   DBUG_ASSERT(row || select_lex->item_list.elements==1);
-  res_type= set_row(select_lex->item_list, item, row, &maybe_null);
+  set_row(select_lex->item_list, row);
   item->collation.set(row[0]->collation);
   if (cols() != 1)
     maybe_null= 0;
@@ -1650,13 +1663,14 @@ void subselect_union_engine::fix_length_and_dec(Item_cache **row)
 
   if (unit->first_select()->item_list.elements == 1)
   {
-    res_type= set_row(unit->types, item, row, &maybe_null);
+    set_row(unit->types, row);
     item->collation.set(row[0]->collation);
   }
   else
   {
-    bool fake= 0;
-    res_type= set_row(unit->types, item, row, &fake);
+    bool maybe_null_saved= maybe_null;
+    set_row(unit->types, row);
+    maybe_null= maybe_null_saved;
   }
 }
 

sql/item_subselect.h

@@ -159,6 +159,7 @@ public:
   my_decimal *val_decimal(my_decimal *);
   bool val_bool();
   enum Item_result result_type() const;
+  enum_field_types field_type() const;
   void fix_length_and_dec();
 
   uint cols();
@@ -311,6 +312,7 @@ protected:
   THD *thd; /* pointer to current THD */
   Item_subselect *item; /* item, that use this engine */
   enum Item_result res_type; /* type of results */
+  enum_field_types res_field_type; /* column type of the results */
   bool maybe_null; /* may be null (first item in select) */
 public:
 
@@ -320,6 +322,7 @@ public:
     result= res;
     item= si;
     res_type= STRING_RESULT;
+    res_field_type= FIELD_TYPE_VAR_STRING;
     maybe_null= 0;
   }
   virtual ~subselect_engine() {}; // to satisfy compiler
@@ -358,6 +361,7 @@ public:
   virtual uint cols()= 0; /* return number of columns in select */
   virtual uint8 uncacheable()= 0; /* query is uncacheable */
   enum Item_result type() { return res_type; }
+  enum_field_types field_type() { return res_field_type; }
   virtual void exclude()= 0;
   bool may_be_null() { return maybe_null; };
   virtual table_map upper_select_const_tables()= 0;
@@ -368,6 +372,9 @@ public:
   virtual bool is_executed() const { return FALSE; }
   /* Check if subquery produced any rows during last query execution */
   virtual bool no_rows() = 0;
+
+protected:
+  void set_row(List<Item> &item_list, Item_cache **row);
 };