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Re: SPARQL 1.1 Query Review Part 1

From: Andy Seaborne <andy.seaborne@epimorphics.com>
Date: Wed, 07 Dec 2011 13:11:12 +0000
Message-ID: <4EDF65F0.1050400@epimorphics.com>
To: public-rdf-dawg@w3.org


On 06/12/11 22:53, Steve Harris wrote:
>>> "[...] In aggregate queries and sub-queries variables that appear
>>> >>  in the query pattern, but are not in the GROUP BY clause cannot be
>>> >>  projected nor used in project expressions." I would add a comma after
>>> >>  "GROUP BY clause"
>> >
>> >  Done
>> >
>>> >>  I don't think this is correct. I can select expressions with aggrated
>>> >>  variables that are not grouped:
>>> >>  SELECT (SAMPLE(?x) AS ?y) { ?x :p ?z } GROUP BY ?z
>> >
>> >  @@Steve
> I believe that's as the group intended.

I think Birte's point is that SAMPLE(?x) uses a variable in a select 
expression, but it's not GROUP BY'ed.

As currently worded, that's not allowed.

>>> >>  "It is an error for aggregates to project variables with a name
>>> >>  already used in other aggregate projections."
>>> >>  Isn't it even forbidden to use any variable that is used elsewhere?
>>> >>  SELECT (SAMPLE(?x) AS ?y) { ?x :p ?y } GROUP BY ?y
>>> >>  would not be valid, right?
>> >
>> >  @@Steve
> I'm not really sure, that seems like more of a general select expressions restriction - I thought that was allowed at one time though?
>
> I guess it wouldn't hurt to reiterate if that is the case, Andy?

Agreed - restate the condition.

	Andy
Received on Wednesday, 7 December 2011 13:11:45 GMT

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