What is {population} of {Hungary} that is {point in time} is {1978-0-0} ?
What was the population of Hungary in 1978?
At the point in time 1978-0-2, what was the population of Hungary?
SELECT ?u WHERE { FILTER ( CONTAINS ( YEAR ( ?o ) , '1978' ) ) . resource:Hungary property:population ?y . ?y property:point_in_time ?o . ?y property:population ?u }
select distinct ?obj  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q28> .
?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> ?obj .
?statement <http://www.wikidata.org/entity/P585> <1978-0-0>
} 

SELECT ?obj WHERE { wd:Q28 p:P1082 ?s . ?s ps:P1082 ?obj . ?s pq:P585 ?x filter(contains(YEAR(?x),'1978')) }