ex11.2.3.2_1.rq

来自「Jena推理机」· RQ 代码 · 共 7 行

PREFIX foaf: <http://xmlns.com/foaf/0.1/>
PREFIX dc:   <http://purl.org/dc/elements/1.1/>
SELECT ?name
 WHERE { ?x foaf:name  ?name .
         OPTIONAL { ?x dc:created ?created } .
         FILTER ( !bound(?created)) }