题解 | 考试分数(四)

select job
        ,case when count(score)%2=0 then ceiling(count(score)/2) else ceiling(count(score)/2)
        end as start
        ,case when count(score)%2=0 then ceiling(count(score)/2+1) else ceiling(count(score)/2)
        end as end
from grade
group by job
order by job;

-- 当个数为偶数时，中位数的起始位置等于个数/2，结束位置等于个数/2+1
-- 当个数为奇数时，中位数的起始位置等于向上取整（个数/2），结束位置等于向
-- 上取整（个数/2）