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今天在坛子上看到了，顺便写下来。
有两种方法：
1、效率不高，因为有子查询。但是简洁。而且我对SOCRES表做了INDEX。所以性能上也差不了多少。
mysql> show create table scores\G
*************************** 1. row ***************************
Table: scores
Create Table: CREATE TABLE `scores` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`score` int(11) DEFAULT '0',
PRIMARY KEY (`id`),
KEY `k_s` (`score`)
) ENGINE=MyISAM AUTO_INCREMENT=1000001 DEFAULT CHARSET=utf8 ROW_FORMAT=DYNAMIC
1 row in set (0.00 sec)
mysql> select count(1) from scores;
+----------+
| count(1) |
+----------+
| 1000000 |
+----------+
1 row in set (0.00 sec)
mysql> select id,score,(select count(1) from scores where score>= (select score
from scores where id = 100 order by score desc limit 1)) as rank from scores whe
re id = 100;
+-----+-------+--------+
| id | score | rank |
+-----+-------+--------+
| 100 | 64 | 370311 |
+-----+-------+--------+
1 row in set (1.05 sec)
2、分句完成。效率高。
存储过程：
DELIMITER $$
DROP PROCEDURE IF EXISTS `test`.`sp_rank`$$
CREATE PROCEDURE `test`.`sp_rank`(IN str_id int(11))
BEGIN
-- user's score
DECLARE str_score int;
-- user's rank
DECLARE rank int;
select score from scores where id = str_id order by score desc limit 1 into str_score ;
select count(*) from scores where score >=str_score into rank;
-- output
select id,score,rank from scores where id = str_id;
END$$
DELIMITER ;
mysql> call sp_rank(100);
+-----+-------+--------+
| id | score | rank |
+-----+-------+--------+
| 100 | 64 | 370311 |
+-----+-------+--------+
1 row in set (1.02 sec)
Query OK, 0 rows affected (1.02 sec)
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