You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'AND (del_user=1 OR del_sender=1)) OR (sender_id= AND (del_user=1 OR del_sender=1' at line 1SELECT user_id, sender_id, subject FROM mail_box WHERE (user_id= AND (del_user=1 OR del_sender=1)) OR (sender_id= AND (del_user=1 OR del_sender=1)) GROUP BY subject ORDER BY mesage_id DESC