题解 | #平均活跃天数和月活人数#注意求活跃天数时要把用户和日期去重
平均活跃天数和月活人数
http://www.nowcoder.com/practice/9e2fb674b58b4f60ac765b7a37dde1b9
select date_format(start_time,'%Y%m') as month, round(count(distinct uid,date_format(start_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 score is not null group by date_format(start_time,'%Y%m')
学而思开奖112人在聊
，可以适当对关键信息加粗一点，比如关键技术、性能指标之类的。