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Re: SELECT to involve expressions [was: Comments list comments]

From: Seaborne, Andy <andy.seaborne@hp.com>
Date: Mon, 21 Mar 2005 17:04:45 +0000
Message-ID: <423EFEAD.60409@hp.com>
To: Dan Connolly <connolly@w3.org>
CC: RDF Data Access Working Group <public-rdf-dawg@w3.org>

Dan Connolly wrote:
> On Mon, 2005-03-21 at 16:04 +0000, Seaborne, Andy wrote:
>>Matters arising from the comments list:
>>1/ SELECT to involve expressions
>>SQL allows constants and expressions in explicit projections (SQL SELECT in 
>>other words)
>>   SELECT ?x "constant" ...
>>   SELECT ?x (?x+?y) ...
>>Combined with nested SELECTs and UNIONs, we would have a way to tag which branch 
>>of a union a solution came from.  This can already be done using different 
>>variables in each branch.
>>This would require access to results by column number (or aliases which are not 
>>required by SQL) and so have impact on the results format.
>>At the moment, SPARQL UNION is defined without the explicit SELECT projection 
>>and is a graph pattern operator.  There is no no assignment of values - it's not 
>>possible to return RDF terms that are not in the graph or a dataset label.


Would need a strong use case to open at this stage.


> let's use technical, rather than (or in addition to) process keywords
> in the subject.
> [2nd issue to follow separately...]
Received on Monday, 21 March 2005 17:05:28 UTC

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