题解 | 插入语句都错啦,两个hard,题目中就一个hard

select
 b.uid as uid,
'activity1' as activity
from examination_info a
inner join exam_record b
on a.exam_id=b.exam_id
and year(b.start_time)='2021'
group by b.uid having min(b.score)>=85
union all
select
 d.uid as uid,
'activity2' as activity
from examination_info c
inner join exam_record d
on c.exam_id=d.exam_id
where year(d.start_time)='2021'
and c.difficulty='hard'
and d.score>80
and timestampdiff(minute,d.start_time,d.submit_time)<c.duration/2
group by d.uid having count(d.score)>=1
order by uid;