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RE: Question regarding subselect

From: Orri Erling <erling@xs4all.nl>
Date: Thu, 30 Apr 2009 13:11:10 +0200
Message-Id: <200904301111.n3UBBTKQ007718@smtp-vbr17.xs4all.nl>
To: "'Orri Erling'" <erling@xs4all.nl>, "'Simon Schenk'" <sschenk@uni-koblenz.de>, "'SPARQL Working Group'" <public-rdf-dawg@w3.org>

Sorry, I was looking at the wrong end of the inbox, the subject is long
gone.

Orri


-----Original Message-----
From: public-rdf-dawg-request@w3.org [mailto:public-rdf-dawg-request@w3.org]
On Behalf Of Orri Erling
Sent: Thursday, April 30, 2009 1:09 PM
To: 'Simon Schenk'; 'SPARQL Working Group'
Subject: RE: Question regarding subselect


Hi


Quite evidently, subselects are meant to work with aggregation, group by,
existence and the like.  Also distinct, order by  and limit / offset can be
scoped to a subselect.  The latter (order, distinct, limit) is not quite in
the spirit of relationality but is very useful in practice.


Orri





-----Original Message-----
From: public-rdf-dawg-request@w3.org [mailto:public-rdf-dawg-request@w3.org]
On Behalf Of Simon Schenk
Sent: Thursday, April 30, 2009 12:48 PM
To: SPARQL Working Group
Subject: Question regarding subselect

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Hi,

I have a question regarding subselects, as the feature has been discussed,
before I joined the WG.

If we do not add any features such as aggregates, scalar expressions,
assignment
or similar - do subselects add anything to the expressiveness of the
language?
All examples in the wiki include at least one such additional feature.

Typical uses such as FORALL or EXISTS should be possible in the current
version
of SPARQL using a combination of OPTIONAL, BOUND filters and perhaps
DISTINCT, I
think.

I would like to understand better the implications of adding subselects and
in
particular dependencies with other features.

Best regards,
Simon
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Received on Thursday, 30 April 2009 11:12:12 GMT

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