Question: Give me a list of all bandleaders that play trumpet.
SPARQL:
PREFIX dbo: <http://dbpedia.org/ontology/> 
PREFIX res: <http://dbpedia.org/resource/> 
SELECT DISTINCT ?uri 
WHERE { 
        ?uri dbo:occupation res:Bandleader . 
        ?uri dbo:instrument res:Trumpet . 
}