Question: Players from how many teams have participated in the National Hockey League?
SPARQL:
SELECT DISTINCT COUNT(?uri) WHERE { ?x <http://dbpedia.org/property/league> <http://dbpedia.org/resource/National_Hockey_League> . ?x <http://dbpedia.org/ontology/team> ?uri  . ?uri <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/SportsTeam>}