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

From: Andy Seaborne <andy.seaborne@epimorphics.com>
Date: Thu, 07 Oct 2010 15:24:24 +0100
Message-ID: <4CADD818.3040708@epimorphics.com>
To: Steve Harris <steve.harris@garlik.com>
CC: Axel Polleres <axel.polleres@deri.org>, SPARQL Working Group <public-rdf-dawg@w3.org>
 > On 2010-10-07, at 02:50, Axel Polleres wrote:
 >
 >> 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"
 >>

I agree that it makes GROUP_CONCAT rather more useful to be able to 
control the order.

On 07/10/10 11:18, Steve Harris wrote:
> My feeling is that you need ORDER BY expression to make it useful.

Agreed.

	Andy

> On 2010-10-07, at 02:50, Axel Polleres wrote:
>
>> 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 14:25:11 GMT

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