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MYSQL实现排名及查询指定用户排名功能(并列排名功能)实例代码

时间:2021-07-01 10:21:17 帮助过:26人阅读

前言

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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;

总结

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