- From: Christophe Guéret <cgueret@few.vu.nl>
- Date: Mon, 27 Sep 2010 12:54:55 +0200
- To: Patrick van Kleef <pkleef@openlinksw.com>
- CC: Linked Data community <public-lod@w3.org>, dbpedia-discussion@lists.sourceforge.net
- Message-ID: <4CA077FF.5070904@few.vu.nl>
Hi Patrick,
>> There seems to be an issue with the SPARQL end point of DBPedia,
>> http://dbpedia.org/sparql.
>>
>> When I run this first query:
>> SELECT ?result WHERE {<http://dbpedia.org/resource/WVNS-DT2>
>> <http://dbpedia.org/ontology/formationDate> ?result. }
>> I get the following result telling me that ?result is a date:
>> <sparql xmlns="http://www.w3.org/2005/sparql-results#"
>> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
>> xsi:schemaLocation="http://www.w3.org/2001/sw/DataAccess/rf1/result2.xsd">
>> <head>
>> <variable name="result"/>
>> </head>
>> <results distinct="false" ordered="true">
>> <result>
>> <binding name="result"><literal
>> datatype="http://www.w3.org/2001/XMLSchema#date">2006-09-13</literal></binding>
>> </result>
>> </results>
>> </sparql>
>>
>> But when I want to find a resource which matches that specific date,
>> no result are returned:
>> SELECT ?result WHERE { ?result
>> <http://dbpedia.org/ontology/formationDate>
>> "2006-09-13"^^<http://www.w3.org/2001/XMLSchema#date>. }
>> gives
>> <sparql xmlns="http://www.w3.org/2005/sparql-results#"
>> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
>> xsi:schemaLocation="http://www.w3.org/2001/sw/DataAccess/rf1/result2.xsd">
>> <head>
>> <variable name="result"/>
>> </head>
>> <results distinct="false" ordered="true">
>> </results>
>> </sparql>
>>
>> Could this be a bug of some sort? I also tried to run the same couple
>> of queries on http://lod.openlinksw.com/sparql and everything works
>> fine there.
>
> We will investigate this and report back to the list.
Thanks for checking this. Just to let you know, I followed Richard
intuition and tried this, which indeed works:
SELECT ?result WHERE { ?result
<http://dbpedia.org/ontology/formationDate> ?date. FILTER(str(?date) =
"2006-09-13") }
Christophe
--
Dr. Christophe Guéret (cgueret@few.vu.nl)
http://cgueret.net
Postdoc working on SOKS (http://www.few.vu.nl/soks)
Knowledge Representation& Reasoning Group
Computational Intelligence Group
Department of Computer Science, AI
VU University Amsterdam
Received on Monday, 27 September 2010 10:55:37 UTC