LeetCode Database: Rank Scores

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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    |
+-------+------+

# Write your MySQL query statement below
select Score, Rank from
(
    select Score, 
    @rank := @rank + if(@prevSc=Score, 0, 1) as Rank,
    @prevSc := Score
    from (select @prevSc := null) x, (select @rank := 0) y,
         (select * from Scores order by Score desc) z
) a;

LeetCode Database: Rank Scores

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原文地址：http://www.cnblogs.com/ydlme/p/4898982.html