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Re: tests around comparators in the graph constraint

From: Steve Harris <S.W.Harris@ecs.soton.ac.uk>
Date: Tue, 14 Dec 2004 10:40:35 +0000
To: RDF Data Access Working Group <public-rdf-dawg@w3.org>
Message-ID: <20041214104035.GD28993@login.ecs.soton.ac.uk>

On Tue, Dec 14, 2004 at 10:06:28AM +0000, Dave Beckett wrote:
> > Simon suggested we look at expressing that in the WHERE clause:
> > 
> >     SELECT ?title ?price
> >      WHERE (?book dc:title ?title)
> >            (?book ns:price ?price)
> >            (?price op:lessThan 42)
> > 
> > which would presumable match the above data. But would it match
> 
> It won't work with any existing RDQL-like system I have seen
> as it is assumes an entirely different operation from matching
> triples and closer to rules.  I oppose this expansion.

+1
it quickly becomes unwieldy if you have some complex expressions,
or functions like

WHERE (?place1 :lat ?lat1)
      (?place1 :long ?long1)
      (?place2 :lat ?lat2)
      (?place2 :long ?long2)
AND :withinKilometers(50.0, ?lat1, ?long1, ?lat2, ?long2)

- Steve
Received on Tuesday, 14 December 2004 10:40:38 GMT

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