Re: Filtering statements in a given named-graph

Hi - the solution with the sameTerm operator works fine.
Thanks
Thomas

Thomas Francart
CTO
Mondeca
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On Mon, Mar 9, 2009 at 4:14 PM, Lee Feigenbaum <lee@thefigtrees.net> wrote:

> Thomas FRANCART wrote:
>
>> Hi SPARQL gurus
>>
>> I have a set of statements separated in 2 named graphs :
>>
>> - some statements appear in named-graph A
>> - some statements appear in named-graph A and named-graph B
>>
>> I would like to make a query on statements that are in named-graph A but
>> _not_ in named-graph B. Is it possible, and how can I do that ?
>>
>> Thanks
>> Thomas
>>
>
> Hi Thomas,
>
> It's possible, but it's not pretty. :-)
>
> Something like this, maybe? (untested)
>
> PREFIX ex: <http://example.org/>
> CONSTRUCT { ?s ?p ?o }
> FROM NAMED ex:A
> FROM NAMED ex:B
> WHERE {
>  GRAPH ex:A {
>    ?s ?p ?o .     # match any triple in A
>  }
>  OPTIONAL {
>    GRAPH ex:B {
>      ?s2 ?p ?o .  # match the same triple in B, introduce a new var
>      FILTER(sameTerm(?s, ?s2)) . # constrain the new var
>    }
>  }
>  FILTER(!bound(?s2)) .   # test that the new var (?s2) was not found
> }
>
> You may also be able to get away with just FILTER(?s = ?s2), but I think
> using sameTerm is slightly more correct in the case that you happen to have
> extended datatypes and an engine that knows about them.
>
> You could also make the graph pattern inside the GRAPH ex:B { ... } clause:
>
>   ?s ?p ?o, ?o2 .
>
> ...and then change the !bound(?s2) to !bound(?o2). Again, untested.
>
> Lee
>