prefix ex:<www.example.org>
premix rdf <...>

SELECT ?creation_date
WHERE
    ?ex:Film:ex:name Titanic
 
SELECT ?film_name 
WHERE {
    ?ex:creation_date ?creation_date .
    ex:name : ?film_name
    FILTER (?creation_date > "1998-01-01"^^xsd:dateTime)
}