Create table If Not Exists Scores (Id int, Score DECIMAL(3,2));
Truncate table Scores;
insert into Scores (Id, Score) values ('', '3.5');
insert into Scores (Id, Score) values ('', '3.65');
insert into Scores (Id, Score) values ('', '4.0');
insert into Scores (Id, Score) values ('', '3.85');
insert into Scores (Id, Score) values ('', '4.0');
insert into Scores (Id, Score) values ('', '3.65');
编写一个 SQL查询 来实现分数排名。如果两个分数相同,则两个分数排名(Rank)应该相同。请注意,平局之后的下一个名次应该是下一个连续的整数值。换句话说,名次之间不应该有“漏洞”。
+----+-------+
| Id | Score |
+----+-------+
| 1 | 3.50 |
| 2 | 3.65 |
| 3 | 4.00 |
| 4 | 3.85 |
| 5 | 4.00 |
| 6 | 3.65 |
+----+-------+
例如,根据给定的上述 Scores
表,您的查询应该生成以下报告(按最高分排序):
+-------+------+
| Score | Rank |
+-------+------+
| 4.00 | 1 |
| 4.00 | 1 |
| 3.85 | 2 |
| 3.65 | 3 |
| 3.65 | 3 |
| 3.50 | 4 |
+-------+------+
第一种解决方法:This one counts, for each score, the number of distinct greater or equal scores.(每条数据循环,求和这个数据相等或者大的个数)
SELECT
Score,
(SELECT count(distinct Score) FROM Scores WHERE Score >= s.Score) Rank
FROM Scores s
ORDER BY Score desc
第二种:与前一个相同,但更快,因为我有一个子查询“首先独立”分数。不完全确定为什么它更快,我猜MySQL做tmp
了一个临时表,并将它用于每个外部分数。
SELECT
Score,
(SELECT count(*) FROM (SELECT distinct Score s FROM Scores) tmp WHERE s >= Score) Rank
FROM Scores
ORDER BY Score desc
第三种:
SELECT s.Score, count(distinct t.score) Rank
FROM Scores s JOIN Scores t ON s.Score <= t.score
GROUP BY s.Id
ORDER BY s.Score desc