思路：first_value求出每个用户的最早登录日期,sum(case when)相等为1，不等为0
select
date
,sum(case when f_d = date then 1 else 0 end) new
from
(
select
user_id
,date
,first_value(date)over(partition by user_id order by date) f_d
from login
) a
group by 1
order by 1