SELECT e.alias, u.nom_usage, a.id
FROM auth_user_md5 as u
LEFT JOIN aliases as e ON(e.type='alias' AND FIND_IN_SET('usage',e.flags) AND e.id = u.user_id)
SELECT e.alias, u.nom_usage, a.id
FROM auth_user_md5 as u
LEFT JOIN aliases as e ON(e.type='alias' AND FIND_IN_SET('usage',e.flags) AND e.id = u.user_id)