题解 | #牛客每个人最近的登录日期(四)#

解题思路： 先选出每个新用户及对应的登录时间，为表a 将表a与选出的时间进行连接 再进行group统计

select date,count(m_date) new
from (select distinct date from login) as d 
left join(select user_id,min(date) m_date
                                        from login
                                        group by user_id) as a
                                        on d.date=a.m_date
group by date
order by date