Hi Esra,
> I installed Virtuoso on Windows. Now I want to work with Sparql queries
> (connected to Openlink Virtuoso on cmd).
>
> I have an rdf file called 'example.rdf'. I want to run this Sparql query:
>
> SPARQL PREFIX ore:<http://www.openarchives.org/ore/terms/> PREFIX
> dc:<http:purl.org/dc/elements/1.1/> SELECT distinct ?resource ?title FROM
> <D:/example.rdf/> WHERE {?resource ore:proxyIn ?proxy . ?resource dc:title
> ?title .};
>
> The result: resource title LONG VARCHAR LONG VARCHAR
>
>
> So I get empty results instead of resource and title values. How can I get
> these two columns?
>
> I'm sure that my Sparql query is correct because I get the title and resource
> values when I am running the same Sparql above on Java or on R.
>
>
> I notice that I get empty result on every running Sparql on Virtuoso. For
> example, also at this query I get empty result:
>
> SPARQL SELECT ?p ?s WHERE { { SELECT DISTINCT ?p ?s FROM <http://dbpedia.org>
> WHERE { ?s ?p <http://dbpedia.org/resource/Germany> } ORDER BY ASC(?p)
> } } OFFSET 50000 LIMIT 1000;
>
> The result of this query: p s LONG VARCHAR LONG VARCHAR
>
> How can I solve this problem? Do I need to install or to do something else
> for running sparql queries? E.g. jena libraries (I have virt_jena.jar file in
> the folder jena and virt_jena2.jar in the folder jena2). Thanks!
Before you can query this data, you first need to load it into your virtuoso
database, which can be done in several ways as described in the following wiki
document:
http://virtuoso.openlinksw.com/dataspace/doc/dav/wiki/Main/VirtRDFInsert
one of the methods uses this function:
http://docs.openlinksw.com/virtuoso/fn_rdf_load_rdfxml_mt.html
Copy your example.rdf file into the same directory where your virtuoso database
is located, as Virtuoso by default is not allowed to read files from your D:
drive.
Make a connection with the isql.exe tool to your virtuoso database and then
perform the following command:
DB.DBA.RDF_LOAD_RDFXML_MT (file_to_string_output ('example.rdf'), '',
'mygraphname');
This command will load the data from the D:/example.rdf file and load it under
the graph name mygraphname.
After this has completed you an use it:
SPARQL
PREFIX ore:<http://www.openarchives.org/ore/terms/>
PREFIX dc:<http:purl.org/dc/elements/1.1/>
SELECT distinct ?resource ?title FROM <mygraphname> WHERE {?resource
ore:proxyIn ?proxy . ?resource dc:title ?title .};
Patrick
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