Cherchons le type de id_biblio
requête : SELECT t.typcategory
FROM pg_attribute a
JOIN pg_type t ON t.oid = a.atttypid
JOIN pg_class c ON c.oid = a.attrelid
WHERE c.relname = 'biblio'
AND a.attname = 'id_biblio'
AND a.attnum > 0id_biblio vaut : N