题解 | #分别满足两个活动的人#

TIMESTAMPDIFF的minute参数有坑，分钟是直接截断的，为了准确用seconds参数

select 
    uid,
    'activity1' as activity
from exam_record
group by uid
having min(score) >= 85

union all

select 
    distinct uid as uid,
    'activity2' as activity
from exam_record a 
inner join examination_info b on a.exam_id=b.exam_id
where b.difficulty='hard' 
    and  (b.duration*60/2 - TIMESTAMPDIFF(SECOND, start_time, submit_time)) >= 0
    and score > 80
order by uid