SELECT t1.id, 'nl' as lang, t1.nl_bez as bez, t1.nl_url as url
FROM test t1
UNION
SELECT t2.id, 'fr' as lang, t2.fr_bez as bez, t2.fr_url as url
FROM test t2
UNION
SELECT t3.id, 'en' as lang, t3.en_bez as bez, t3.en_url as url
FROM test t3