题解 | #SQL69:每日新登录用户数#
牛客每个人最近的登录日期(四)
http://www.nowcoder.com/practice/e524dc7450234395aa21c75303a42b0a
对于每个用户来说,只有他第一次登录的那天 他才是新用户
select t.date, sum(case when t.date=t.min_date then 1 else 0 end) as new from ( select date, min(date) over(partition by user_id) as min_date from login ) t group by date order by date