高频 SQL 50 题（基础版）_1141. 查询近30天活跃用户数
1141. 查询近30天活跃用户数
select activity_date day,count(distinct user_id) active_users
from Activity
where (activity_date<='2019-07-27'
and activity_date>DATE_sub('2019-07-27',INTERVAL 30 DAY))
group by(activity_date)
select activity_date day,count(distinct user_id) active_users
from Activity
where (activity_date<='2019-07-27'
and activity_date>DATE_sub('2019-07-27',INTERVAL 30 DAY))
group by(activity_date)