题解 | #试卷发布当天作答人数和平均分#

#请计算每张SQL类别试卷发布后，当天5级以上的用户作答的 人数uv 和 平均分avg_score，按人数降序，相同人数的按平均分升序
select exam_id,count(distinct uid,start_time) uv,round(avg(score),1) avg_score
from user_info
    left join exam_record using(uid)
    left join examination_info using(exam_id)
where level>5 and tag='SQL' and DATE(release_time)=date(start_time)
group by exam_id
order by uv desc,avg_score