题解 | #考试分数(三)#

使用开窗函数解决，在每个分区内进行排名，选择排名小于等于2的

SELECT
    c.id,c.name,c.score
FROM
    (select g1.id,l1.name,g1.score,DENSE_RANK() over(partition by l1.name order by g1.score DESC) d 
    FROM grade g1 join language l1 on g1.language_id=l1.id ) c
WHERE 
    c.d<=2
order by c.name,c.score desc,c.id

但是有一疑问，over（）内的order by 似乎只能加一个参数（不太懂）