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）相同。请注意，平分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“间隔”。
+----+-------+ | Id | Score | +----+-------+ | 1 | 3.50 | | 2 | 3.65 | | 3 | 4.00 | | 4 | 3.85 | | 5 | 4.00 | | 6 | 3.65 | +----+-------+
例如，根据上述给定的 Scores 表，你的查询应该返回（按分数从高到低排列）：
+-------+------+ | Score | Rank | +-------+------+ | 4.00 | 1 | | 4.00 | 1 | | 3.85 | 2 | | 3.65 | 3 | | 3.65 | 3 | | 3.50 | 4 | +-------+------+
解法一：对于每一个分数，从表中找出有多少个大于或等于该分数的不重复分数，然后降序排列
select Score,
(select count(distinct Score) from Scores as s2 where s2.Score >= s1.Score) Rank
from Scores as s1
order by Score DESC;
解法二：使用联结 join，当左表的分数小于等于右表的分数时，对右表的分数进行计数（即计算有几个不重复的分数大于自己，计算结果就是rank），然后根据id分组后，再根据分数降序排列
select s1.Score, count(distinct s2.Score) Rank
from Scores as s1 join Scores as s2 on s1.Score <= s2.Score
group by s1.Id
order by s1.Score DESC;
