What is {member of sports team} of {Iker Casillas} that is {start time} is {1999-1-1} ?
Who became a member of the sports team Iker Casillas on January 1st, 1991?
What is the member of a sports team of Iker Casillas that starts January 1st, 1991?
SELECT ?h WHERE { resource:Iker_Casillas property:member_of_sports_team ?b . ?b property:start_time ?o . FILTER ( CONTAINS ( YEAR ( ?o ) , '1999' ) ) . ?b property:member_of_sports_team ?h }
select distinct ?obj  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q11584> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P54> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> ?obj .
?statement <http://www.wikidata.org/entity/P580> <1999-1-1>
} 

SELECT ?obj WHERE { wd:Q11584 p:P54 ?s . ?s ps:P54 ?obj . ?s pq:P580 ?x filter(contains(YEAR(?x),'1999')) }