Question: Who produced the most films?
SPARQL query:
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX onto: <http://dbpedia.org/ontology/>
SELECT ?uri ?string
WHERE 
{
	?film rdf:type onto:Film .
        ?film onto:producer ?uri .
        OPTIONAL {?uri rdfs:label ?string . FILTER (lang(?string) = 'en') }
} ORDER BY DESC(COUNT(?film)) LIMIT 1