//MySQL 8.0写法
select * from(
  select row_number() over (partition by UserName order by CheckTime desc) as rn,u.*
  from kq_record u where CheckDate = ‘2018-03-31 00:00:00‘
) t where t.rn=1

//MySQL 5.7 比如一个用户多条登录记录取最后时间
select max.*, MAX(max.CheckTime) createMax
From (select * from kq_record where CheckDate = ‘2020-12-02 00:00:00‘ order by CheckTime desc) max
group by UserName,InOrOut