题解 | #牛客每个人最近的登录日期(四)#
牛客每个人最近的登录日期(四)
https://www.nowcoder.com/practice/e524dc7450234395aa21c75303a42b0a
select
date,
count(distinct case when date = first_login_date then user_id else null end) as new
from
(
select
user_id,
date,
first_value(date) over(partition by user_id) as first_login_date
from login
) t0
group by date
order by date asc
考察开窗函数first_value；
注意处理某一天没有用户登录的情况
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