mysql子查询批量找id最大的

 $sql = "select a.id as max_id,a.uid from
(
SELECT
   `uid`,
    id
FROM
   (`users_level_change_log`)
WHERE
   `uid` IN (
      ".$uids_str."
   )
AND `level_type` = 2
AND `create_time` < '{$now_month}'
order by id desc ) as a group by a.uid";