题解 | SQL270题。

select id,job,score,t_rank from(
    select *,rank() over(partition by job order by score desc) t_rank from grade g
    left join(
        select job,floor((count(*)+1)/2) start, floor((count(*)+2)/2) `end` 
        from grade
        group by job
    ) l using(job)
) c
where t_rank= start or t_rank=`end`
order by id 
-- 先取得中位数位置，之后利用窗口函数给出序号，按照序号是否对应中位数位置进行输出