题解 | 牛客直播各科目出勤率
牛客直播各科目出勤率
https://www.nowcoder.com/practice/0cab547df4f0430b93042128f445d899
select t1.course_id,course_name,round((count1/count2)*100,2) attend_rate from (select at.course_id course_id,course_name,count(distinct user_id) count1 from attend_tb at join course_tb ct on at.course_id = ct.course_id where timestampdiff(minute,in_datetime,out_datetime) >= 10 group by at.course_id,course_name) as t1 join (select course_id,count(1) count2 from behavior_tb bt where if_sign = 1 group by course_id) as t2 on t1.course_id = t2.course_id order by t1.course_id