题解 | #牛客每个人最近的登录日期(五)#

笨办法，将中位数和每个grade对应的排名区间列出来，中位数在排名区间内选中即可

with total as
(select sum(number) tnum from class_grade)
select grade from
(
select *
,sum(number) over(order by grade) - number + 1 as floor
,sum(number) over(order by grade) as celling
,floor(((select tnum from total)+1)/2) as lowm
,floor(((select tnum from total)+2)/2) as upperm
from class_grade c
)a
where (lowm>=floor and lowm<=celling) or (upperm>=floor and celling>=upperm)