[Mulgara-general] Substring Function in Sparql?

Stone Xiang stone.xiang at yahoo.com
Mon Aug 24 22:08:02 UTC 2009


That's good to know. Good luck with your moving.



________________________________
From: Paul Gearon <gearon at ieee.org>
To: Mulgara General <mulgara-general at mulgara.org>
Sent: Monday, August 24, 2009 1:31:01 PM
Subject: Re: [Mulgara-general] Substring Function in Sparql?

Not for a couple of weeks. I'm moving house right now (I'm only online
now because I had to check email from a tradesman, and I'm using a
friend's computer), and I won't be online again until next week.

It's an easy job, so I'll probably do it first thing, as a way of
getting myself back into the swing of coding.  :-)

Paul

On 8/24/09, Stone Xiang <stone.xiang at yahoo.com> wrote:
> That would be great. When will this feature be available?
>
>
>
>
> ________________________________
> From: Paul Gearon <gearon at ieee.org>
> To: Mulgara General <mulgara-general at mulgara.org>
> Sent: Friday, August 21, 2009 5:29:39 PM
> Subject: Re: [Mulgara-general] Substring Function in Sparql?
>
> On Fri, Aug 21, 2009 at 2:14 PM, Stone Xiang<stone.xiang at yahoo.com> wrote:
>> The scenario is a (not so elegant) extension of the Fedora repository,
>> where
>> the objects
>> in the RELS-EXT datastream are used to store some data values. A more
>> appropriate
>> example would be:
>> SELECT $s from <#ri> {$s <some predicate> $t}
>> order by substring($t, 5, 3)
>> Here the subject of <some predicate> is the URI of a Fedora item while the
>> object stores
>> several fields of data and one of them is relevant to sorting (or other
>> filtering
>> operations).
>> Since you already said there is no substring fuctino in Sparql, I think
>> I'll
>> find some other
>> way around.
>
> Not in standard SPARQL, but I'm sure that some implementation will
> have this function available. I've been looking to add extra functions
> myself (it's VERY easy). I'd offer to do it here right now, only I
> haven't implemented ORDER BY for arbitrary expressions yet. You'd have
> to set a variable. So it would probably end up as:
>
>   SELECT $s from <#ri>
>   WHERE {$s <some predicate> $t . LET ($ord := fn:substring($t, 5, 3)}
>   ORDER BY $ord
>
> Regards,
> Paul
> _______________________________________________
> Mulgara-general mailing list
> Mulgara-general at mulgara.org
> http://mulgara.org/mailman/listinfo/mulgara-general
>
>
>
>
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