Hi, labels in Wikidata are multilingual and are mapped to RDF literals with a language tag. This query finds three results (though only one of them has a date of birth): SELECT ?_Geburtsdatum WHERE { ?s ?label "Brian O'Nolan"@en. OPTIONAL { ?s wdt:P569 ?_Geburtsdatum. } } This one, on the other hand, only has one result (@de instead of @en): SELECT ?_Geburtsdatum WHERE { ?s ?label "Brian O'Nolan"@de. OPTIONAL { ?s wdt:P569 ?_Geburtsdatum. } } I hope that helps. Cheers, Lucas On 02.04.2017 08:33, Detlef Küchler wrote: > Hi, > > I got the following problem. If I use the search field of the main page > searching for "Brian O'Nolan" I get a result. > But if I use the following piece of code in the query service no > result shows up. > > SELECT ?_Geburtsdatum WHERE { > ?s ?label "Brian O'Nolan". > OPTIONAL { ?s wdt:P569 ?_Geburtsdatum. } > } > > What I'm doing wrong? Is it a problem of coding the apostrophe? > If yes, how do I have to code it? > > Best regards > Detlef >