On 9 May 2014 11:38, Alejandro Rodríguez González
<[email protected]> wrote:
> Hi all,
>
> Maybe this question has been already answered or is in the documentation,
> but I can't find an answer.
>
> I have a code to perform a set of SPARQL queries against a concrete
> dataset. My problem is that, the SPARQL query is making use of datatype()
> function, and it seems that Jena is not recognizing this function (and
> therefore return me an error).
>
> The query that I want to perform is the following:
>
> *SELECT distinct datatype(?o) as ?datatype*
The syntax is:
SELECT distinct (datatype(?o) as ?datatype)
The () are not to do with DISTINCT, they come from the AS part:
(expression AS ?variable)
> *FROM <@NAMED_GRAPH>*
> *WHERE {*
> * ?s a <@SUBJECT_TYPE> .*
> *?s <@PREDICATE_TYPE> ?o . *
> * FILTER isLiteral(?o)*
> *}*
> *group by ?o*
>
>
> Originally it was "SELECT distinct(datatype(?o)) as ?datatype" but I saw
> that distinct should be used without parenthesis. (I also try with "SELECT
> distinct datatype ?o as..." with no positive result).
>
> An example of the query:
>
> SELECT distinct datatype(?o) as ?datatype
> FROM <http://bio2rdf.org/bio2rdf.dataset:bio2rdf-affymetrix-20131220>
> WHERE {
> ?s a <http://bio2rdf.org/affymetrix_vocabulary:Genechip-Array> .
> ?s <http://bio2rdf.org/affymetrix_vocabulary:x-unigene> ?o .
> FILTER isLiteral(?o)
> }
> group by ?o
>
> If I perform the query against the endpoint (
> http://s4.semanticscience.org:14001/sparql), it runs fine (in this case is
> not returning any result, but no errors are thrown):
>
> http://s4.semanticscience.org:14001/sparql?default-graph-uri=&query=SELECT+distinct+datatype%28%3Fo%29+as+%3Fdatatype%0D%0AFROM+%3Chttp%3A%2F%2Fbio2rdf.org%2Fbio2rdf.dataset%3Abio2rdf-affymetrix-20131220%3E%0D%0AWHERE+%7B%0D%0A+%3Fs+a+%3Chttp%3A%2F%2Fbio2rdf.org%2Faffymetrix_vocabulary%3AGenechip-Array%3E+.%0D%0A%3Fs+%3Chttp%3A%2F%2Fbio2rdf.org%2Faffymetrix_vocabulary%3Ax-unigene%3E+%3Fo+.+++%0D%0A+FILTER+isLiteral%28%3Fo%29%0D%0A%7D%0D%0Agroup+by+%3Fo&format=text%2Fhtml&timeout=0&debug=on
>
> However, when I use my code (which generates the query ok, I check it
> printing the query), it returns the following exception:
> http://pastebin.com/qhzyxJKn
>
> The code which performs the query is here (the method which throws the
> exception is the QueryFactory.create(..): http://pastebin.com/2VVgKyZT
>
> I guess that it is a problem "calling" datatype function, but not sure how
> to solve it.
>
> Thanks!
>
> --
> Dr. Alejandro Rodríguez González - PhD
>
> Bioinformatics at Centre for Plant Biotechnology and Genomics UPM-INIA
> Polytechnic University of Madrid
> http://www.alejandrorg.com
> Phone: +34 914524900 . Ext: 25550
>
>
> *Once the game is over, the king and the pawn go back in the same box. -
> Italian proverb*
