(select
 (order
  (leftjoin
   (bgp
     (triple ?:x <http://xmlns.com/foaf/0.1/name> ?:name))
   (bgp
     (triple ?:x <http://xmlns.com/foaf/0.1/mbox> ?:mbox)))
  ((asc ?:mbox)))
 (?:name ?:mbox))