On 29/09/11 14:10, Luis Daniel Ibáñez González wrote:
Hi,
I've been playing with Jena (v. 2.6.4 with ARQ 2.8.7) using dbpedia's
endpoint, and the following query:
SELECT ?title (GROUP_CONCAT(?platforms) AS ?plat)
WHERE
{ ?game<http://purl.org/dc/terms/subject> <
http://dbpedia.org/resource/Category:First-person_shooters> .
?game foaf:name ?title .
?game dbpprop:platforms ?platforms
}
GROUP BY ?title
parsed from String with the proper constructor yields:
Exception in thread "main" HttpException: HttpException: 400 Bad Request:
HttpException: 400 Bad Request
at
com.hp.hpl.jena.sparql.engine.http.HttpQuery.execCommon(HttpQuery.java:337)
at
com.hp.hpl.jena.sparql.engine.http.HttpQuery.execGet(HttpQuery.java:189)
at
com.hp.hpl.jena.sparql.engine.http.HttpQuery.exec(HttpQuery.java:144)
at
com.hp.hpl.jena.sparql.engine.http.QueryEngineHTTP.execSelect(QueryEngineHTTP.java:133)
at jenatest.Main.main(Main.java:58)
either using default syntax or ARQ syntax.
If i use "Count" it works with both syntax.
Nothing special with the factories, I used:
Query query = QueryFactory.create(queryString,Syntax.syntaxARQ);
QueryExecution qexec = QueryExecutionFactory.sparqlService("
http://dbpedia.org/sparql";, query);
before the execution.
Am I doing something wrong?
No -- what it means is that DBPedia does not support GROUP_CONCAT.
400 (Bad Request) is almost certainly "syntax error". Try their UI.
QueryEngineHTTP.execSelect sends the whole query (after local checking)
to the far end.
Andy
Thanks in advance for your help.
