MySQL实现排名并查询指定用户排名功能

表结构:
CREATE TABLE test.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
AUTO_INCREMENT = 1
CHARACTER SET utf8
COLLATE utf8_general_ci
COMMENT = '测试排序'
ROW_FORMAT = DYNAMIC;
 
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。
 
实现排名:
方法一:
SELECT t.*, @rownum := @rownum + 1 AS rownum
FROM (SELECT @rownum := 0) r, (SELECT * FROM testsort ORDER BY score DESC) AS t;
 
方法二:
SELECT t.*, @rownum := @rownum + 1 AS rownum
FROM (SELECT @rownum := 0) r, testsort AS t
ORDER BY t.score DESC;
 
结果:
 
 
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 = 222;
 
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 = 222;
 
结果:
 
 
实现从指定用户uid为111,222,333,444,555 中获取uid为222的排名
SELECT b.* FROM
(
SELECT t.*, @rownum := @rownum + 1 AS rownum
FROM (SELECT @rownum := 0) r,
(SELECT * FROM testsort WHERE uid IN (111,222,333,444,555) ORDER BY score DESC) AS t
) AS b WHERE b.uid = 222;

结果:

posted @ 2018-05-22 18:08 一个人的孤独自白 阅读(...) 评论(...) 编辑 收藏