Search in a multilingual database for terms that have not been translated into a specific language

问题

My query in a multilingual thesaurus looks like this:

select (COUNT(?label) as ?pCount)
where {?term <http://www.w3.org/2004/02/skos/core#prefLabel> ?label 
FILTER(langMatches(lang(?label), "DE"))}

I get a huge number of concepts with their German translation, which is what I expect from this query.
I'm now looking for a query giving me all concepts without any German translation, that is all which have no "prefLabel" with "@de".

How would such a query look like?

回答1:

You want either FILTER NOT EXISTS or MINUS:

select ?term
where {
    ?term a <http://www.w3.org/2004/02/skos/core#Concept>
    MINUS {
        ?term <http://www.w3.org/2004/02/skos/core#prefLabel> ?label
        FILTER(langMatches(lang(?label), "DE"))
    }
}

Either will work here (I've used MINUS because it's shorter).

With MINUS the matching rows of the right hand (or, rather, bottom) block are removed from the other side. In this case terms with german labels are removed from the list of all concepts (?term a <http://www.w3.org/2004/02/skos/core#Concept>).

(If your concepts aren't explicitly typed as such you could use ?term <http://www.w3.org/2004/02/skos/core#prefLabel> ?someLabel instead, but you might want to add a DISTINCT to tidy up)

来源：https://stackoverflow.com/questions/16415515/search-in-a-multilingual-database-for-terms-that-have-not-been-translated-into-a