SPARQL queries don't work with Jena

Question

I'm constantly having the following problem. When I write queries into Jena they don't work.

Take for example this good query from other sites:

PREFIX dbpedia: <http://dbpedia.org/resource/>
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
PREFIX mo: <http://purl.org/ontology/mo/>

SELECT *
WHERE {dbpedia:The_Beatles mo:member ?member .
       ?member foaf:name ?name
      }

when I translate it into Java's Jena it should look like this:

public static String beatlesMembers = 
        "PREFIX dbpedia: <http://dbpedia.org/resource/> "+
        "PREFIX foaf: <http://xmlns.com/foaf/0.1/> "+
        "PREFIX mo: <http://purl.org/ontology/mo/> "+
        "SELECT * " +
        "WHERE {dbpedia:The_Beatles mo:member ?member . "+
        "?member foaf:name ?name "+
        "}";

and then I query DBPEDIA

Query query = QueryFactory.create(Requests.beatlesMembers);

QueryExecution qexec = QueryExecutionFactory.sparqlService("http://dbpedia.org/sparql", query);

try {
    ResultSet results = qexec.execSelect();
    for (; results.hasNext();) {
        QuerySolution s = results.nextSolution();
        System.out.println(s.toString());
    }
}
finally {
   qexec.close();
}

And it returns nothing...

Any idea why? I can't figure out how to correctly write these queries in Java. Hope you can help.

Thank you very much for your help

Answer 1

Did you try the query at dbpedia.org?

When I run it there, through the web form interface, I get zero rows.

{ dbpedia:The_Beatles mo:member ?member } has zero matches. There are no http://purl.org/ontology/mo/ triples.

Try { dbpedia:The_Beatles ?pred ?obj} and look at the details.