Question: Who are the producers of the movies  which has music by Gary Chang ?
SPARQL:
SELECT DISTINCT ?uri WHERE { ?x <http://dbpedia.org/property/music> <http://dbpedia.org/resource/Gary_Chang> . ?x <http://dbpedia.org/property/producer> ?uri . ?x <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/Film>}