思路：中位数正序>=1/2 total 倒序也一样
select
id
,job
,score
,rk2 t_rank
from
(
select
*
,count(score)over(partition by job) as total
,row_number()over(partition by job order by score) as rk1
,row_number()over(partition by job order by score desc) as rk2
from grade
) a
where rk1 >= total/2 and rk2 >= total/2
order by id