Fixed bug #28898.

For a join query with GROUP BY and/or ORDER BY and a view reference
in the FROM list the metadata erroneously showed empty table aliases
and database names for the view columns.



sql/item.h:
  Fixed bug #28898.
  Body of Item_ref::get_tmp_table_item method has been moved
  to item.cc file.
mysql-test/t/metadata.test:
  Updated test case for bug #28898.
sql/item.cc:
  Fixed bug #28898.
  The Item_ref::get_tmp_table_item method has been modified
  to copy pointers to the table alias and database name to the new
  Item_field object created for a field stored in the temporary
  table.
mysql-test/r/metadata.result:
  Updated test case for bug #28898.
sql/sql_select.cc:
  Fixed bug #28898.
  The change_to_use_tmp_fields function has been modified to
  to copy pointers to the table alias and database name from
  the Item_ref objects to the new Item_field objects created
  for fields stored in the temporary table.

mysql-test/r/metadata.result

@@ -140,4 +140,45 @@ Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is
 def			a	v_small	v_small	3	9	9	N	32769	0	63
 v_small
 214748364
+CREATE TABLE t1 (c1 CHAR(1));
+CREATE TABLE t2 (c2 CHAR(1));
+CREATE VIEW v1 AS SELECT t1.c1 FROM t1;
+CREATE VIEW v2 AS SELECT t2.c2 FROM t2;
+INSERT INTO t1 VALUES ('1'), ('2'), ('3');
+INSERT INTO t2 VALUES ('1'), ('2'), ('3'), ('2');
+SELECT v1.c1 FROM v1 JOIN t2 ON c1=c2 ORDER BY 1;
+Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
+def	test	t1	v1	c1	c1	254	1	1	Y	0	0	8
+c1
+1
+2
+2
+3
+SELECT v1.c1, v2.c2 FROM v1 JOIN v2 ON c1=c2;
+Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
+def	test	t1	v1	c1	c1	254	1	1	Y	0	0	8
+def	test	t2	v2	c2	c2	254	1	1	Y	0	0	8
+c1	c2
+1	1
+2	2
+3	3
+2	2
+SELECT v1.c1, v2.c2 FROM v1 JOIN v2 ON c1=c2 GROUP BY v1.c1;
+Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
+def	test	t1	v1	c1	c1	254	1	1	Y	32768	0	8
+def	test	t2	v2	c2	c2	254	1	1	Y	0	0	8
+c1	c2
+1	1
+2	2
+3	3
+SELECT v1.c1, v2.c2 FROM v1 JOIN v2 ON c1=c2 GROUP BY v1.c1 ORDER BY v2.c2;
+Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
+def	test	t1	v1	c1	c1	254	1	1	Y	32768	0	8
+def	test	t2	v2	c2	c2	254	1	1	Y	0	0	8
+c1	c2
+1	1
+2	2
+3	3
+DROP VIEW v1;
+DROP TABLE t1,t2;
 End of 5.0 tests

mysql-test/t/metadata.test

@@ -90,5 +90,26 @@ select a.* from (select 2147483648 as v_large) a;
 select a.* from (select 214748364 as v_small) a;
 --disable_metadata
 
+#
+# Bug #28898: table alias and database name of VIEW columns is empty in the
+# metadata of # SELECT statement where join is executed via temporary table.
+#
+
+CREATE TABLE t1 (c1 CHAR(1));
+CREATE TABLE t2 (c2 CHAR(1));
+CREATE VIEW v1 AS SELECT t1.c1 FROM t1;
+CREATE VIEW v2 AS SELECT t2.c2 FROM t2;
+INSERT INTO t1 VALUES ('1'), ('2'), ('3');
+INSERT INTO t2 VALUES ('1'), ('2'), ('3'), ('2');
+
+--enable_metadata
+SELECT v1.c1 FROM v1 JOIN t2 ON c1=c2 ORDER BY 1;
+SELECT v1.c1, v2.c2 FROM v1 JOIN v2 ON c1=c2;
+SELECT v1.c1, v2.c2 FROM v1 JOIN v2 ON c1=c2 GROUP BY v1.c1;
+SELECT v1.c1, v2.c2 FROM v1 JOIN v2 ON c1=c2 GROUP BY v1.c1 ORDER BY v2.c2;
+--disable_metadata
+
+DROP VIEW v1;
+DROP TABLE t1,t2;
 
 --echo End of 5.0 tests

sql/item.cc

@@ -5501,6 +5501,21 @@ void Item_ref::make_field(Send_field *field)
 }
 
 
+Item *Item_ref::get_tmp_table_item(THD *thd)
+{
+  if (!result_field)
+    return (*ref)->get_tmp_table_item(thd);
+
+  Item_field *item= new Item_field(result_field);
+  if (item)
+  {
+    item->table_name= table_name;
+    item->db_name= db_name;
+  }
+  return item;
+}
+
+
 void Item_ref_null_helper::print(String *str)
 {
   str->append(STRING_WITH_LEN("<ref_null_helper>("));

sql/item.h

@@ -1904,11 +1904,7 @@ public:
   enum_field_types field_type() const   { return (*ref)->field_type(); }
   Field *get_tmp_table_field()
   { return result_field ? result_field : (*ref)->get_tmp_table_field(); }
-  Item *get_tmp_table_item(THD *thd)
-  { 
-    return (result_field ? new Item_field(result_field) :
-                          (*ref)->get_tmp_table_item(thd));
-  }
+  Item *get_tmp_table_item(THD *thd);
   table_map used_tables() const		
   {
     return depended_from ? OUTER_REF_TABLE_BIT : (*ref)->used_tables(); 

sql/sql_select.cc

@@ -14241,6 +14241,13 @@ change_to_use_tmp_fields(THD *thd, Item **ref_pointer_array,
 	if (!item_field)
 	  DBUG_RETURN(TRUE);                    // Fatal error
 	item_field->name= item->name;
+        if (item->type() == Item::REF_ITEM)
+        {
+          Item_field *ifield= (Item_field *) item_field;
+          Item_ref *iref= (Item_ref *) item;
+          ifield->table_name= iref->table_name;
+          ifield->db_name= iref->db_name;
+        }
 #ifndef DBUG_OFF
 	if (_db_on_ && !item_field->name)
 	{