what is the {start time} for {Charlie Chaplin} has {spouse} as {Oona O'Neill} ?
What is the date that Charlie Chaplin and Oona O'Neill's got married?
When did Charlie Chaplin and Oona O'Neill get married?
SELECT ?v WHERE { ?x property:start_time ?v . ?x property:spouse resource:Oona_O'Neill . resource:Charlie_Chaplin property:spouse ?x }
select distinct ?value  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q882> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P26> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> <http://wikidata.dbpedia.org/resource/Q137808> .
?statement <http://www.wikidata.org/entity/P580> ?value. 
} 

SELECT ?value WHERE { wd:Q882 p:P26 ?s . ?s ps:P26 wd:Q137808 . ?s pq:P580 ?value}