How many {set in period} are to/by {World War II} ?
WWII took place in what era?
what era was world war 2?
SELECT ( COUNT ( ?w ) AS ?f ) { ?w property:set_in_period resource:World_War_II }
SELECT (COUNT(?sub) AS ?subs ) {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> ?sub .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P2408> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> http://wikidata.dbpedia.org/resource/Q362 .
} 

SELECT (COUNT(?sub) AS ?value ) { ?sub wdt:P2408 wd:Q362 }
44