SPARQL select optional with language

Question

I have some triples that look like this:

test:thing rdfs:label \"Non-Language Label\"
test:thing rdfs:label \"English Label\"@en
test:thing rdfs:label \"French L         


        

Answer 1

The easiest way to check the language of literals is to use the lang() function. Using this, your query can be written as:

PREFIX rdfs:  
PREFIX test:  
SELECT ?label ?preferredLabel 
WHERE { 
   test:thing rdfs:label ?label 
   OPTIONAL { 
     test:thing rdfs:label ?preferredLabel . 
     FILTER (lang(?preferredLabel) = "" || lang(?preferredLabel) = "fr") 
   } 
}