Hello Rajeev,
SPARQL-compilant way is
select ?s, ?label where { ?s rdfs:label ?label FILTER(
> langMatches(?label, "ml_IN") || langMatches(?label, "en_IN") ||
> lang(?label) = "" ). } order by ?s
then do application-level sorting.
Virtuoso-specific way could be
select ?s (bif:coalesce (?mllabel, ?enlabel, ?label)) as ?label
where {
graph ?g {
{ ?s rdfs:label ?label . FILTER(langMatches(?label, "ml_IN") ||
langMatches(?label, "en_IN") || lang(?label) = "" ) }
optional { ?s rdfs:label ?mllabel . FILTER(langMatches(?mllabel,
"ml_IN")) }
optional { ?s rdfs:label ?enlabel . FILTER(langMatches(?enlabel,
"en_IN")) } } }
order by ?s
but that's inefficient. In SQL it could be possible to write
user-defined aggregate that work like MAX() but choose one best readable
value out of a given list rather than the biggest one out of the list.
Unfortunately, Virtuoso SPARQL does not support user-defined aggregates
ATM.
Best Regards,
Ivan Mikhailov,
OpenLink Software.
On Thu, 2008-04-03 at 09:59 +0530, Rajeev J Sebastian wrote:
> Hello all friends,
>
> I want to write a query for retrieving rdfs:label's in a
> localization-capable way. I.e., I want to be able to do something like
>
> select ?s, ?label where { ?s rdfs:label ?label FILTER(
> langMatches(?label, "ml_IN, en_IN") ). }
>
> In other words, I want a "cascade" of languages i.e., select the ml_IN
> label if it exists, else fallback to the en_IN label, else fallback to
> label with no language set.
>
> Is this possible in Virtuoso SPARQL ? from the langMatches spec on the
> W3C site and the RFC, I think it is not possible. Could someone give
> some hint how I can achieve this effectively ?
>
> Regards
> Rajeev J Sebastian
>
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