题解 | #分别满足两个活动的人#

select * from
(select uid
,'activity1' as activity
from exam_record
where uid not in (
    select uid from exam_record
    where score < 85
) and year(submit_time) = 2021
) as x

union

(select distinct uid
,'activity2' as activity
from exam_record er
join examination_info ei on er.exam_id = ei.exam_id
where 
timestampdiff(minute, start_time, submit_time) < duration / 2 and 
difficulty = 'hard' 
and score > 80
and year(submit_time) = 2021)

order by uid
;