新加一列注册日期，注册日期就是登入日期最小值，统计登入日期等于注册日期的行
select date
       ,sum(if(date=reg_date,1,0)) as new
from
(
    select user_id
           ,date
           ,min(date) over (partition by user_id) as reg_date
    from login
) as a
group by date