SELECT u.*,
       r.autocompletion,
       (SELECT COUNT(DISTINCT a.user_id)
        FROM   emissions e
               INNER JOIN abonnements a
                 ON a.emission_id = e.id
        WHERE  e.main_rea = u.id
                OR Find_in_set(u.id, e.others_rea) > 0) AS abonn
FROM   users u
       LEFT JOIN realisateurs r
         ON r.user_id = u.id
WHERE  u.user_type = "realisateur"