Leetcode 178. Rank Scores (Database)

参考： https://my.oschina.net/Tsybius2014/blog/493244

常见的排序1. 排名1,2,3，...，n 不对重复的分数做特殊处理

Score  Rank

100     1

99     2

99     3

98     4

90     5

# Write your MySQL query statement below
select Score, @Counter := @Counter + 1 as rank
from Scores, (select @Counter := 0) as C
order by Score desc;

排序2. 相同分数排名相同，排名第n名表示前面有n-1个人，而不是n-1个分数。

Score  Rank

100     1

99     2

99     2

98     4

90     5

# Write your MySQL query statement below
select S1.Score, (
select count(Score) + 1
from Scores S2
where S1.Score < S2.Score )
as Rank
from Scores S1 order by Score desc

排序3. 相同分数排名相同，第n名表示前面有n-1个分数。

Score  Rank

100     1

99     2

99     2

98     3

90     4

# Write your MySQL query statement below
select s.Score, count(distinct t.Score) Rank
from Scores s join Scores t on s.Score <= t.Score    #join 和 inner join是
group by s.Id
order by s.Score desc;