题解 | 最受欢迎的top3课程
最受欢迎的top3课程
https://www.nowcoder.com/practice/b9b33659559c46099aa3257da0374a48
select c.cid, count(c.id) pv, sum(timestampdiff(minute,start_time,end_time)) time_len from play_record_tb p left join course_info_tb c on p.cid = c.cid where timestampdiff(day,release_date,start_time)<=7 group by c.cid having avg(score)>=3 order by time_len desc limit 3
注意限定条件有个一周内 这个容易忽略
