what is the {point in time} for {Durham} has {population} as {6679.0} ?
At what time did Durham have 6679 people living there?
When did Durham had a population of 6679 people?
SELECT ?e WHERE { resource:Durham property:population ?y . ?y property:population ?h . FILTER ( ?h = 6679.0 ) . ?y property:point_in_time ?e }
select distinct ?value  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q49229> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P1082> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> <6679.0> .
?statement <http://www.wikidata.org/entity/P585> ?value. 
} 

SELECT ?value WHERE { wd:Q49229 p:P1082 ?s . ?s ps:P1082 ?x filter(contains(?x , '6679.0')) . ?s pq:P585 ?value}