178.LeetCode 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    |
+-------+------+
================================================================================
思路：先查出来score的排名在inner join Scores表。

SELECT
	s1.score,
	s2.rank
FROM
	Scores s1,
	(
		SELECT
			s.score,
			(
				SELECT
					count(1)
				FROM
					(
						SELECT DISTINCT
							score
						FROM
							Scores
					) t
				WHERE
					t.score >= s.score
			) rank
		FROM
			(
				SELECT DISTINCT
					score
				FROM
					Scores
			) s
	) s2
WHERE
	s1.score = s2.score
ORDER BY
	rank ASC