W3C home > Mailing lists > Public > public-rdf-dawg@w3.org > July to September 2005

Re: Review: Query Result Form --> need COUNT ?

From: Seaborne, Andy <andy.seaborne@hp.com>
Date: Tue, 05 Jul 2005 10:13:12 +0100
Message-ID: <42CA4F28.70309@hp.com>
To: Souripriya Das <souripriya.das@oracle.com>
CC: public-rdf-dawg@w3.org

Souripriya Das wrote:
> I am not sure if COUNT is allowed. So, if someone needs to find the 
> cardinality of the solution set, does SPARQL (based on 1.406) allow this?
> If not, would something like this work?
> 
>   SELECT COUNT
>   WHERE ...


One issue in adding this in this form is that later, a WG might wish to add 
grouping and aggregation.  So a form of COUNT which as COUNT(*) might be better 
including COUNT(?x) of distinct ?x (unbound may or may not count)

Also, so far, we have not forced pattern solutions to retain duplicates or to 
implicitly apply DISTINCT (before or after projection) - it allows wider 
implementation choices - so there are a few details outstanding.

> 
> In a similar way, does it make sense to try allowing ASK as part of 
> SELECT as follows:
>  
>   SELECT EXISTS
>    WHERE ...

That would be a more consistent approach, removing the need for a special case 
for ASK.  It would have lead to better compositionality long term.

	Andy

> 
> Thanks,
> - Souri.
> 
Received on Tuesday, 5 July 2005 09:13:40 GMT

This archive was generated by hypermail 2.3.1 : Tuesday, 26 March 2013 16:15:23 GMT