[GENERAL] self-join on subselect

[PFC]

    How do you do a self-join on a subselect ?
        like
        SELECT a.x+b.x FROM (subselect) a, (subselect) b WHERE a.id = b.id+10
	but without performing the subselect twice  
..................................?

---------------------------(end of broadcast)---------------------------
TIP 9: the planner will ignore your desire to choose an index scan if your
     joining column's datatypes do not match