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