题解 | #分别满足两个活动的人#

select distinct uid,'activity1'as activity
from exam_record
where score>=85
and submit_time is not null
and year(submit_time) = 2021
and uid not in 
            (select distinct uid 
            from exam_record
            where score<85)

union all

select distinct uid,'activity2'as activity
from exam_record
where uid in
(select uid
from exam_record as a
join examination_info as b
on a.exam_id=b.exam_id
where 
difficulty='hard'
and timestampdiff(SECOND,start_time,submit_time)<=duration*30
and score>80
and submit_time is not null
and year(submit_time) = 2021)


order by uid