[LeetCode]-DataBase-Rank Scores

Write a SQL query to rank scores. If there is a tie between two scores, both should have the same ranking. Note that after a tie, the next ranking number should be the next consecutive integer value. In other words, there should be no "holes" between ranks.

+----+-------+
| Id | Score |
+----+-------+
| 1  | 3.50  |
| 2  | 3.65  |
| 3  | 4.00  |
| 4  | 3.85  |
| 5  | 4.00  |
| 6  | 3.65  |
+----+-------+

For example, given the above Scores table, your query should generate the following report (order by highest score):

+-------+------+
| Score | Rank |
+-------+------+
| 4.00  | 1    |
| 4.00  | 1    |
| 3.85  | 2    |
| 3.65  | 3    |
| 3.65  | 3    |
| 3.50  | 4    |
+-------+------+

需求：给值排序，相同的值序列号相同，且序号连续
分析：需要使用到Mysql的用户自定义变量

CREATE TABLE Scores(
Id TINYINT UNSIGNED,
Score DECIMAL(10,2)
)ENGINE=MyISAM;

-- SQL 用户自定义变量
SELECT t1.Score,t1.Rank
FROM (
SELECT s.Score,@curRank:=@curRank+IF(@prevScore = s.Score, 0, 1) AS 'Rank',@prevScore:=s.Score
FROM Scores s,(SELECT @curRank:=0) c,(SELECT @prevScore:=NULL) p
ORDER BY s.Score DESC
) t1