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Re: still not understanding FROM NAMED

From: Bob DuCharme <bob@snee.com>
Date: Wed, 17 Nov 2010 07:50:02 -0500
Message-ID: <4CE3CF7A.80907@snee.com>
To: Rob Vesse <rav08r@ecs.soton.ac.uk>
CC: public-sparql-dev@w3.org
That makes sense, but if I can do this

    SELECT ?classTitle
    WHERE {
      GRAPH <http://example.com/classes/new/201106>
      { ?s <http://example.com/ns/sample#classTitle> ?classTitle } .

does FROM NAMED add anything besides the ability to list a few graphs 
and then says GRAPH ?varName so that the graph pattern is applied to 
several graphs?



On 11/17/2010 4:24 AM, Rob Vesse wrote:
> FROM NAMED specifies Graphs that are used in GRAPH clauses
> e.g.
> SELECT * FROM NAMED<http://example.org/myGraph>  WHERE { ?s ?p ?o . GRAPH
> ?g { ?s ?x ?y }}
> Would first find all triples from the default graph (which may in fact be
> the union of several graphs) and then the GRAPH part would use Graphs
> specified in FROM NAMED clauses to match additional triples.  At least
> broadly speaking that is how it should work.  Actual implementations tend
> to vary somewhat.
> The difference should be that a FROM clause specifies a graph that forms
> part of the default graph over which the query operates while the FROM
> NAMED specifies Graphs used only in Graph clauses
> Rob
> On Tue, 16 Nov 2010 19:29:23 -0500, Bob DuCharme<bob@snee.com>  wrote:
>> I understand the various examples in the SPARQL spec that use FROM
>> NAMED, but I still don't completely understand what the FROM NAMED part
>> does, especially compared with FROM<http://some/uri>.
>> http://www.w3.org/TR/2010/WD-sparql11-query-20101014/#namedGraphs says
>> "A query can supply IRIs for the named graphs in the RDF Dataset using
>> the FROM NAMED clause." If they're named graphs, don't they already have
>> IRIs as names? What is FROM NAMED adding here?
>> thanks,
>> Bob
Received on Wednesday, 17 November 2010 12:50:31 UTC

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