题解 | #最差是第几名(二)#

中位数所在区间为最大正序数与最大逆序数均>=二分之一总序数的区间.

select grade from (
select * ,
       (select sum(number) as sum from class_grade) as sum,
       sum(number) over(order by grade) as nx,
       sum(number) over(order by grade desc) as zx
from class_grade) as a
where a.nx>=sum/2 and a.zx>=sum/2
order by grade asc;