题解 | #试卷发布当天作答人数和平均分#

select
exam_id,
count(distinct uid) uv,
round(avg(score),1) avg_score
from
exam_record
where
(exam_id,date(start_time))
in
(select
exam_id,
date(release_time) day
from
examination_info
where tag='SQL')
and
uid
in
(select 
uid
from
user_info
where
level >5)
group by exam_id
order by uv desc,avg_score