# optJoin1
# from http://www.w3.org/2008/07/MappingRules/#optJoin1 Revision: 1.38 
# $Id: query_spec-optJoin1.rq,v 1.3 2008/09/26 18:30:59 eric Exp $

PREFIX emplP: <http://hr.example/DB/Employee#>
PREFIX mangP: <http://hr.example/DB/Manage#>

SELECT ?empName ?managName ?grandManagName
 WHERE {          ?emp            emplP:lastName   ?empName .
         OPTIONAL { ?mang         mangP:manages    ?emp .
                    ?mang         mangP:manager    ?manager .
                    ?manager      emplP:lastName   ?managName .
                    ?grandMang    mangP:manages    ?manager .
                    ?grandMang    mangP:manager    ?grandManager .
                    ?grandManager emplP:lastName   ?grandManagName } }