|
Hi, how can I select all music files that
has no performer? What I do now is use the following select
and check the result, if the second value is blank, then that song has no
performer, Track-sparql –q “SELECT ?song ?performer
WHERE { OPTIONAL { ?song nmm:performer ?performer} } GROUP by (?performer)” Is there a better way? Say SELECT ?song WHERE {!{?song
nmm:performer ?performer}} ? Thanks! |