https://leetcode-cn.com/problems/rank-scores/

178. 分数排名

 

select s1.Score, count(distinct s2.Score) as Rank from scores as s1, scores as s2 where s1.Score <= s2.Score group by s1.Id order by s1.Score desc;

具体思路就是把一个表变成两个表，然后进行比较

具体说一下为什么要用group by ，如果不用group by的话，原先的数据集是一个大组，只会对一行进行处理。而group by之后，是分成多个小组，然后每一个小组分别取进行处理