除了ai那个回答,你也可以先排序,再分组
比如
select user_id from(
select user_id from log order by ID desc limit 9999999
) group by user_id
就是数量大的话会有性能问题
还可以
select
user_id,
(select max(time) from log as l2 where l2.user_id = l1.user_id) as newLoginTime from log as l1
group by user_id