MYSQL成绩排名

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)