题解 | #牛客每个人最近的登录日期(四)#

select
    date,
    sum(
        case
            when (user_id, date) in (
                select
                    user_id,
                    min(date) date
                from
                    login
                group by
                    user_id
            ) then 1
            else 0
        end
    ) as new
from
    login
group by
    date
order by
    date