Question: How many companies have launched their rockets from the Vandenerg Air base?
SPARQL query:
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX onto: <http://dbpedia.org/ontology/>
SELECT DISTINCT COUNT(?uri) WHERE { ?x onto:launchSite <http://dbpedia.org/resource/Vandenberg_Air_Force_Base> . ?x onto:manufacturer ?uri  . ?uri rdf:type onto:Company}