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More Aggregates questions ... Another scalar parameter for GROUP_CONCAT?

From: Axel Polleres <axel.polleres@deri.org>
Date: Wed, 6 Oct 2010 21:50:36 -0400
Message-Id: <A4073ABE-0733-48EC-B623-3F6B338F0B89@deri.org>
To: SPARQL Working Group <public-rdf-dawg@w3.org>
When thinking about practical examples for GROUP_CONCAT, I can hardly think of any where I wouldn't want to impose an order...
... thus, what's the opinions about adding another scalar parameter "order" which takes as parameter  "DESC"|"ASC"

That is, e.g. something like:

    PREFIX foaf: <http://xmlns.com/foaf/0.1/>
    SELECT ( SAMPLE(?N) as ?Name)
       ( GROUP_CONCAT(?M; SEPARATOR = ", " , ORDER="ASC") AS ?Nicknames )
WHERE { ?P a foaf:Person ;
           foaf:name ?N ;
           foaf:nick ?M . }
GROUP BY ?P 

It seems that GROUP_CONCAT in SQL dialects also has an ORDER BY clause, as e.g. a quick google search reveals for MySQL [1].

Steve, do you think that would be a big deal to add?
Others?

Axel

P.S.: I thought briefly about not only allowing "ASC"|"DESC" but an arbitrary ORDER BY expression, however, that admittedly seems not 
to go well with the current Aggregation() semantics definition, I am afraid...


1. http://dev.mysql.com/doc/refman/5.0/en/group-by-functions.html#function_group-concat
Received on Thursday, 7 October 2010 01:51:14 GMT

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