│B+> 27158     if (resolution == RESOLVED_BEHIND_ALIAS &&

│    27159         order_item->fix_fields_if_needed_for_order_by(thd, order->item)) 

│    27160       return TRUE; 

│    27161

│    27162     /* Lookup the current GROUP field in the FROM clause. */ 

│    27163     order_item_type= order_item->type(); 

│    27164     DBUG_ASSERT( order_item_type == (*order->item)->type() );       

CREATE TABLE t2 ( a INT ); 

INSERT INTO t2 VALUES (1),(2),(1),(4),(2);

SELECT alias.a FROM t2, ( SELECT * FROM t2 ) AS alias GROUP BY alias.a;