MySQL实现排名并查询指定用户排名功能，并列排名功能

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：

实现并列排名（相同分数排名相同）：

SELECT

obj.uid,

obj.score,

CASE

WHEN @rowtotal = obj.score THEN

@rownum

WHEN @rowtotal := obj.score THEN

@rownum :=@rownum + 1

WHEN @rowtotal = 0 THEN

@rownum :=@rownum + 1

END AS rownum

FROM

(

SELECT

uid,

score

FROM

testsort

ORDER BY

score DESC

) AS obj,

(SELECT @rownum := 0 ,@rowtotal := NULL) r

查询指定用户并列排名:

SELECT total.* FROM

(SELECT

obj.uid,

obj.score,

CASE

WHEN @rowtotal = obj.score THEN

@rownum

WHEN @rowtotal := obj.score THEN

@rownum :=@rownum + 1

WHEN @rowtotal = 0 THEN

@rownum :=@rownum + 1

END AS rownum

FROM

(

SELECT

uid,

score

FROM

testsort

ORDER BY

score DESC

) AS obj,

(SELECT @rownum := 0 ,@rowtotal := NULL) r) AS total WHERE total.uid = 222;