按年份获取特定行的排名

Question

如何在一年的同月期间进行查询以获取行的排名，与该行与其他行的votes数相比？

+----+---------+--------+---------------------+
| id | post_id | votes  |        date         |
+----+---------+--------+---------------------+
|  1 |       1 |  10342 | 2015-04-29 04:40:51 |
|  2 |       2 |   9432 | 2015-04-17 22:37:53 |
| 3  |      3  | 33064  | 2015-05-17 22:37:17 |
| 4  |      4  | 32741  | 2015-05-17 22:37:25 |
| 5  |      5  | 30362  | 2015-05-17 22:37:31 |
| 6  |      6  | 15321  | 2015-06-28 00:33:20 |
| 7  |      1  |  4356  | 2015-06-28 00:19:30 |
+----+---------+--------+---------------------+

例如，如果我想在每个月找到post_id＃1的等级，它应该返回如下内容：

+----+------+---------+-------+---------------------+
| id | rank | post_id | votes |        date         |
+----+------+---------+-------+---------------------+
|  1 |    1 |       1 | 10342 | 2015-04-29 04:40:51 |
| 7  |    2 |      1  | 4356  | 2015-06-28 00:19:30 |
+----+------+---------+-------+---------------------+

这是因为post_id＃1在一年中的第四个月票数最多，但是在今年第六个月中票数第二高。

如何进行此查询？

Answer 1

SELECT YEAR(t1.date) AS year, MONTH(t1.date) AS month, SUM(IF(t1.votes >= t2.votes, 1, 0)) AS rank
FROM YourTable AS t1
JOIN YourTable AS t2 ON YEAR(t1.date) = YEAR(t2.date) AND MONTH(t1.date) = MONTH(t2.date)
WHERE t2.post_id = 1
GROUP BY year, month

DEMO