Database error 
            SELECT *
            FROM tbl__contractor_doc
            WHERE tbl_obj_id IN (
              SELECT distinct tbl_obj_id
              FROM tbl__contractor2activity
              WHERE kind_of_activity IN (164))
            AND active = 1
            AND tbl_obj_id != "10428"
            AND registration_confirmed=1
            ORDER BY rand()
            LIMIT 4