题解 | #平均活跃天数和月活人数#
平均活跃天数和月活人数
https://www.nowcoder.com/practice/9e2fb674b58b4f60ac765b7a37dde1b9
select date_format(submit_time, '%Y%m') as month, round((count(distinct uid, date_format(submit_time, '%y%m%d'))) / count(distinct uid), 2) as avg_active_days, count(distinct uid) as mau from exam_record where year(start_time)=2021 and submit_time is not null group by date_format(submit_time, '%Y%m')
count(distinct 参数1，参数2) 只要两个参数有一个不一样就会返回该条记录
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