MySQL实现排名查询并指定用户查看排名
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阅读目录
表结构
CREATE TABLE `testsort` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`uid` int(11) DEFAULT '0' COMMENT '用户id',
`score` decimal(10,2) DEFAULT '0.00' COMMENT '分数',
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
INSERT INTO `tts`.`testsort` (`id`, `uid`, `score`)
VALUES
('1', '1', '1.00'),
('2', '1', '2.00');
INSERT INTO `tts`.`testsort` (`id`, `uid`, `score`)
VALUES
;
INSERT INTO `tts`.`testsort` (`id`, `uid`, `score`)
VALUES
('3', '1', '3.00');
INSERT INTO `tts`.`testsort` (`id`, `uid`, `score`)
VALUES
('4', '6', '4.00');
INSERT INTO `tts`.`testsort` (`id`, `uid`, `score`)
VALUES
('5', '8', '5.00');
INSERT INTO `tts`.`testsort` (`id`, `uid`, `score`)
VALUES
('6', '9', '6.00');
INSERT INTO `tts`.`testsort` (`id`, `uid`, `score`)
VALUES
('7', '1', '7.00');
INSERT INTO `tts`.`testsort` (`id`, `uid`, `score`)
VALUES
('8', '1', '7.00');
INSERT INTO `tts`.`testsort` (`id`, `uid`, `score`)
VALUES
('9', '1', '8.00');
INSERT INTO `tts`.`testsort` (`id`, `uid`, `score`)
VALUES
('10', '1', '8.00');
INSERT INTO `tts`.`testsort` (`id`, `uid`, `score`)
VALUES
('11', '1', '9.00');
INSERT INTO `tts`.`testsort` (`id`, `uid`, `score`)
VALUES
('12', '1', '9.00');
INSERT INTO `tts`.`testsort` (`id`, `uid`, `score`)
VALUES
('13', '1', '1.00');
INSERT INTO `tts`.`testsort` (`id`, `uid`, `score`)
VALUES
('14', '1', '2.00');
INSERT INTO `tts`.`testsort` (`id`, `uid`, `score`)
VALUES
('15', '1', '2.00');
INSERT INTO `tts`.`testsort` (`id`, `uid`, `score`)
VALUES
('16', '1', '3.00');
实现排名
思路：可以先排序，再对结果进行编号；也可以先查询结果，再排序编号。
说明：
@rownum := @rownum + 1 中 := 是赋值的作用，这句话的意思是先执行 @rownum + 1，然后把值赋给 @rownum；
(SELECT @rownum := 0) r 这句话的意思是设置 rownum 字段的初始值为 0 ，即编号从 1 开始。
方法一
SELECT
t.*, @rownum := @rownum + 1 AS rownum
FROM
(SELECT @rownum := 0) r,
(
SELECT
*
FROM
testsort
ORDER BY
score DESC
) AS t;
+----+------+-------+--------+
| id | uid | score | rownum |
+----+------+-------+--------+
| 12 | 1 | 9.00 | 1 |
| 11 | 1 | 9.00 | 2 |
| 9 | 1 | 8.00 | 3 |
| 10 | 1 | 8.00 | 4 |
| 7 | 1 | 7.00 | 5 |
| 8 | 1 | 7.00 | 6 |
| 6 | 9 | 6.00 | 7 |
| 5 | 8 | 5.00 | 8 |
| 4 | 6 | 4.00 | 9 |
| 16 | 1 | 3.00 | 10 |
| 3 | 1 | 3.00 | 11 |
| 2 | 1 | 2.00 | 12 |
| 14 | 1 | 2.00 | 13 |
| 15 | 1 | 2.00 | 14 |
| 13 | 1 | 1.00 | 15 |
| 1 | 1 | 1.00 | 16 |
+----+------+-------+--------+
16 rows in set (0.00 sec)
方法二
SELECT
t.*, @rownum := @rownum + 1 AS rownum
FROM
(SELECT @rownum := 0) r,
testsort AS t
ORDER BY
t.score DESC;
+----+------+-------+--------+
| id | uid | score | rownum |
+----+------+-------+--------+
| 12 | 1 | 9.00 | 1 |
| 11 | 1 | 9.00 | 2 |
| 9 | 1 | 8.00 | 3 |
| 10 | 1 | 8.00 | 4 |
| 7 | 1 | 7.00 | 5 |
| 8 | 1 | 7.00 | 6 |
| 6 | 9 | 6.00 | 7 |
| 5 | 8 | 5.00 | 8 |
| 4 | 6 | 4.00 | 9 |
| 16 | 1 | 3.00 | 10 |
| 3 | 1 | 3.00 | 11 |
| 2 | 1 | 2.00 | 12 |
| 14 | 1 | 2.00 | 13 |
| 15 | 1 | 2.00 | 14 |
| 13 | 1 | 1.00 | 15 |
| 1 | 1 | 1.00 | 16 |
+----+------+-------+--------+
16 rows in set (0.00 sec)
查看指定用户排名
方法一
SELECT
b.*
FROM
(
SELECT
t.*, @rownum := @rownum + 1 AS rownum
FROM
(SELECT @rownum := 0) r,
(
SELECT
*
FROM
testsort
ORDER BY
score DESC
) AS t
) AS b
WHERE
b.uid = 9;
+----+------+-------+--------+
| id | uid | score | rownum |
+----+------+-------+--------+
| 6 | 9 | 6.00 | 7 |
+----+------+-------+--------+
1 row in set (0.00 sec)
方法二
SELECT
b.*
FROM
(
SELECT
t.*, @rownum := @rownum + 1 AS rownum
FROM
(SELECT @rownum := 0) r,
testsort AS t
ORDER BY
t.score DESC
) AS b
WHERE
b.uid = 8;
+----+------+-------+--------+
| id | uid | score | rownum |
+----+------+-------+--------+
| 5 | 8 | 5.00 | 8 |
+----+------+-------+--------+
1 row in set (0.00 sec)
实现从指定用户uid为 1,6,8,9 中获取 uid 为 6 的排名
SELECT
b.*
FROM
(
SELECT
t.*, @rownum := @rownum + 1 AS rownum
FROM
(SELECT @rownum := 0) r,
(
SELECT
*
FROM
testsort
WHERE
uid IN (1, 6, 8, 9)
ORDER BY
score DESC
) AS t
) AS b
WHERE
b.uid = 6;
+----+------+-------+--------+
| id | uid | score | rownum |
+----+------+-------+--------+
| 4 | 6 | 4.00 | 9 |
+----+------+-------+--------+
1 row in set (0.00 sec)
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