Count the number of musical work which were sold by Sony Music?
SELECT DISTINCT COUNT(?uri) WHERE { ?x <http://dbpedia.org/property/label> <http://dbpedia.org/resource/Sony_Music_Entertainment> . ?uri <http://dbpedia.org/property/music> ?x  . ?uri <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/MusicalWork>}
Sony_Music_Entertainment