- rank()
按照某字段的排序结果添加排名，但它是跳跃的、间断的排名，例如两个并列第一名后，下一个是第三名。
SELECT Score,rank() over(ORDER BY Score desc) as 'Rank' FROM score;
# 分组排序
SELECT Score,rank() over([partition by xxx] ORDER BY Score desc) as 'Rank' FROM score;
- row_number()
它是将某字段按照顺序依次添加行号。
SELECT Score,row_number() over(ORDER BY Score desc) as 'Rank' FROM score；
# 分组排序
SELECT Score,row_number() over([partition by xxx] ORDER BY Score desc) as 'Rank' FROM score；
- dense_rank()
dense 英语中指“稠密的、密集的”。dense_rank()是的排序数字是连续的、不间断。当有相同的分数时，它们的排名结果是并列的，例如，1,2,2,3。
SELECT Score,dense_rank() over(ORDER BY Score desc) as 'Rank' FROM score；
# 分组排序
SELECT Score,dense_rank() over([partition by xxx] ORDER BY Score desc) as 'Rank' FROM score；
4.总结
对比分析rank(), dense_rank(), row_number()
- 案例
create table score(
Id INT NOT NULL PRIMARY KEY auto_increment,
Score decimal(5,2) NOT NULL
);
insert score(Score)
values(88),
(56),
(77),
(88),
(75),
(77),
(56),
(33);
select * from score;
select Id, Score, DENSE_RANK() OVER(ORDER BY Score DESC) AS `Rank`
from score;
dense_rank()应用示例
