Question: Count the number of first drivers in all the GPs where Mika Hakkinen was a first driver?
SPARQL:
SELECT DISTINCT COUNT(?uri) WHERE { ?x <http://dbpedia.org/ontology/poleDriver> <http://dbpedia.org/resource/Mika_Häkkinen> . ?x <http://dbpedia.org/ontology/firstDriver> ?uri  . ?uri <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/RacingDriver>}