How many people have been trained in an institute located in California?
SELECT DISTINCT COUNT(?uri) WHERE { ?x <http://dbpedia.org/property/city> <http://dbpedia.org/resource/California> . ?uri <http://dbpedia.org/property/training> ?x  . ?uri <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/Person>}
California