题解 | #最差是第几名(二)#
最差是第几名(二)
http://www.nowcoder.com/practice/165d88474d434597bcd2af8bf72b24f1
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;