题解 | #分别满足两个活动的人#

select uid, 'activity1' as activity
from exam_record left join examination_info using(exam_id)
where year(start_time)=2021
group by uid
having min(score)>=85
union
select uid, 'activity2' as activity
from exam_record left join examination_info using(exam_id)
where year(start_time)=2021 and score>80 and
unix_timestamp(submit_time)-unix_timestamp(start_time)<=duration*30
and difficulty='hard'
group by uid
order by uid