Hello Sebastian,
If ?app always gets exactly one value, what's the purpose in the
subquery?
If you're not sure that ?app is the only (e.g., if triple ?app
nao:identifier "nepomukindexer" can appear in more than one graph), then
you can write, of course,
select distinct ?r where {
graph ?g {
?r nie:url ?url .
} .
?g nao:maintainedBy ?app .
filter (?app = (select ?a where { ?a nao:identifier "nepomukindexer" }))
}
or even shorter
select distinct ?r where {
graph ?g {
?r nie:url ?url .
} .
?g nao:maintainedBy `(select ?a where { ?a nao:identifier "nepomukindexer"
})` .
}
Best Regards,
Ivan Mikhailov
OpenLink Software
http://virtuoso.openlinksw.com
On Mon, 2011-07-04 at 14:42 +0200, Sebastian Trüg wrote:
> Hi list,
>
> in a query like this:
>
> select distinct ?r where {
> graph ?g {
> ?r nie:url ?url .
> } .
> ?g nao:maintainedBy ?app .
> ?app nao:identifier "nepomukindexer" .
> }
>
> I would like to use a sub-query to replace ?app since there is only
> exactly one resource which has this identifier. The simplest possibility
> is to use two queries and cache the resource URI of the app in the
> client. But I figure there could be a fancy sub-query which allowed me
> to query the app in-place.
>
> Is that possible?
>
> Cheers,
> Sebastian
>
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