what is the {start time} for {William Henry Harrison} has {position held} as {President of the United States} ?
which year  william Henry Harrison roll  President of the United States?
When was William Henry Harrison President of the United States?
SELECT ?l WHERE { ?n property:position_held resource:President_of_the_United_States . resource:William_Henry_Harrison property:position_held ?n . ?n property:start_time ?l }
select distinct ?value  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q11869> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P39> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> <http://wikidata.dbpedia.org/resource/Q11696> .
?statement <http://www.wikidata.org/entity/P580> ?value. 
} 

SELECT ?value WHERE { wd:Q11869 p:P39 ?s . ?s ps:P39 wd:Q11696 . ?s pq:P580 ?value}