# 看总数 总数%2=1 中位数就是len/2 和 len/2+1 # 总数%2=0 中位数就是(len+1)/2 with A as ( select grade ,sum(number)over(order by grade)e ,round(len/2)d ,round(len%2)mo from class_grade join ( select sum(number)len from class_grade )a ) # 偏移一下 ,B as ( select grade ,lag(e,1,0)over(order by grade)b ,e ,d ,mo f...