- From: Lee Feigenbaum <lee@thefigtrees.net>
- Date: Wed, 12 Nov 2008 20:09:50 -0500
- To: Jaroslav Pullmann <jaroslav.pullmann@fit.fraunhofer.de>
- CC: public-sparql-dev@w3.org
Jaroslav Pullmann wrote:
>
> Hello,
> to check for property cardinalities within an RDF document I used
> following queries:
>
> - for cardinality 0-1: NOT(Q2)
> - for cardinality 1: Q1 AND NOT(Q2)
> - for cardinality 1-n : Q1
>
>
> # Q1
> ASK
> WHERE
> {
> ?s rdf:type pfx:Foo; pfx:bar ?b .
> }
>
> # Q2 - no solutions, no duplicates
> ASK
> WHERE
> {
> ?s rdf:type pfx:Foo;
> pfx:bar ?b;
> pfx:bar ?b1
> FILTER(?b != ?b1)
> }
>
> Could these queries be formulated in a simpler, more elegant way ?
I agree with Axel that in standard SPARQL these are basically the way to
go. Just wanted to point out:
http://esw.w3.org/topic/SPARQL/Extensions/Aggregates
Several SPARQL implementations extend SPARQL with a COUNT() function
that would make this much easier. For example, using Glitter (Open
Anzo), I'd write:
SELECT (COUNT(?o) AS ?cardinality)
WHERE {
?s a pfx:Foo ; pfx:bar ?o .
}
Lee
Received on Thursday, 13 November 2008 01:11:05 UTC