题解 | #统计作答次数#
平均活跃天数和月活人数
http://www.nowcoder.com/practice/9e2fb674b58b4f60ac765b7a37dde1b9
#GROUP BY MONTH(submit_time); 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 submit_time is not NULL AND year(submit_time)= 2021 GROUP BY DATE_FORMAT(submit_time,'%Y%m');
