Question: Give me a list of all trumpet players that were bandleaders.
SPARQL:
PREFIX dbo: <http://dbpedia.org/ontology/>
PREFIX res: <http://dbpedia.org/resource/>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
SELECT DISTINCT ?uri ?string WHERE
{
	?uri dbo:occupation res:Bandleader .
	?uri dbo:instrument res:Trumpet . 
        OPTIONAL { ?uri rdfs:label ?string. FILTER (lang(?string) = 'en') }
}