what is the {start time} for {Deutsche Bahn} has {manager/director} as {Hartmut Mehdorn} ?
Harmut Mehdorn became director at Deutsche Bahn when?
When was Hartmut Mehdorn appointed a director at Deutsche Bahn?
SELECT ?q WHERE { ?f property:start_time ?q . resource:Deutsche_Bahn property:director_/_manager ?f . ?f property:director_/_manager resource:Hartmut_Mehdorn }
select distinct ?value  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q9322> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P1037> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> <http://wikidata.dbpedia.org/resource/Q91984> .
?statement <http://www.wikidata.org/entity/P580> ?value. 
} 

SELECT ?value WHERE { wd:Q9322 p:P1037 ?s . ?s ps:P1037 wd:Q91984 . ?s pq:P580 ?value}