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 (user_id,date) in
(select user_id,min(date)
from login
group by user_id) then user_id
else null
end)
from login
group by date
order by date;
找到首次登录的用id
case
when (user_id,date) in
(select user_id,min(date)
from login
group by user_id) then user_id
else null
end)
对日期进行分类、排序
group by date order by date;
完整代码如下
select date
,count(distinct
case
when (user_id,date) in
(select user_id,min(date)
from login
group by user_id) then user_id
else null
end)
from login
group by date
order by date;
