Fixed bug #26209.

The function make_unireg_sortorder ignored the fact that any
view field is represented by a 'ref' object.
This could lead to wrong results for the queries containing
both GROUP BY and ORDER BY clauses.

mysql-test/r/view.result

@@ -3117,4 +3117,22 @@ Warnings:
 Note	1003	select `test`.`t1`.`f1` AS `f1`,`test`.`t1`.`f2` AS `f2` from `test`.`t1` order by `test`.`t1`.`f1`,`test`.`t1`.`f2`
 drop view v1;
 drop table t1;
+CREATE TABLE t1 (
+id int(11) NOT NULL PRIMARY KEY,
+country varchar(32),
+code int(11) default NULL
+);
+INSERT INTO t1 VALUES
+(1,'ITALY',100),(2,'ITALY',200),(3,'FRANCE',100), (4,'ITALY',100);
+CREATE VIEW v1 AS SELECT * FROM t1;
+SELECT code, COUNT(DISTINCT country) FROM t1 GROUP BY code ORDER BY MAX(id);
+code	COUNT(DISTINCT country)
+200	1
+100	2
+SELECT code, COUNT(DISTINCT country) FROM v1 GROUP BY code ORDER BY MAX(id);
+code	COUNT(DISTINCT country)
+200	1
+100	2
+DROP VIEW v1;
+DROP TABLE t1;
 End of 5.0 tests.

mysql-test/t/view.test

@@ -3038,4 +3038,24 @@ explain extended select * from v1 order by f1;
 drop view v1;
 drop table t1;
 
+#
+# Bug#26209: queries with GROUP BY and ORDER BY using views 
+#
+
+CREATE TABLE t1 (
+  id int(11) NOT NULL PRIMARY KEY,
+  country varchar(32),
+  code int(11) default NULL
+);
+INSERT INTO t1 VALUES
+  (1,'ITALY',100),(2,'ITALY',200),(3,'FRANCE',100), (4,'ITALY',100);
+
+CREATE VIEW v1 AS SELECT * FROM t1;
+
+SELECT code, COUNT(DISTINCT country) FROM t1 GROUP BY code ORDER BY MAX(id);
+SELECT code, COUNT(DISTINCT country) FROM v1 GROUP BY code ORDER BY MAX(id);
+
+DROP VIEW v1;
+DROP TABLE t1;
+
 --echo End of 5.0 tests.

sql/sql_select.cc

@@ -12744,15 +12744,15 @@ SORT_FIELD *make_unireg_sortorder(ORDER *order, uint *length,
 
   for (;order;order=order->next,pos++)
   {
-    pos->field=0; pos->item=0;
-    if (order->item[0]->type() == Item::FIELD_ITEM)
-      pos->field= ((Item_field*) (*order->item))->field;
-    else if (order->item[0]->type() == Item::SUM_FUNC_ITEM &&
-	     !order->item[0]->const_item())
-      pos->field= ((Item_sum*) order->item[0])->get_tmp_table_field();
-    else if (order->item[0]->type() == Item::COPY_STR_ITEM)
+    Item *item= order->item[0]->real_item();
+    pos->field= 0; pos->item= 0;
+    if (item->type() == Item::FIELD_ITEM)
+      pos->field= ((Item_field*) item)->field;
+    else if (item->type() == Item::SUM_FUNC_ITEM && !item->const_item())
+      pos->field= ((Item_sum*) item)->get_tmp_table_field();
+    else if (item->type() == Item::COPY_STR_ITEM)
     {						// Blob patch
-      pos->item= ((Item_copy_string*) (*order->item))->item;
+      pos->item= ((Item_copy_string*) item)->item;
     }
     else
       pos->item= *order->item;