问题描述

我需要找出客户的等级.在这里，我根据我的要求添加了相应的 ANSI 标准 SQL 查询.请帮我把它转换成 MySQL.

I need to find out rank of customers. Here I am adding the corresponding ANSI standard SQL query for my requirement. Please help me to convert it to MySQL .

SELECT RANK() OVER (PARTITION BY Gender ORDER BY Age) AS [Partition by Gender], 
  FirstName, 
  Age,
  Gender 
FROM Person

MySQL 中是否有查询排名的函数?

Is there any function to find out rank in MySQL?

推荐答案

一种选择是使用排名变量，例如:

One option is to use a ranking variable, such as the following:

SELECT    first_name,
          age,
          gender,
          @curRank := @curRank + 1 AS rank
FROM      person p, (SELECT @curRank := 0) r
ORDER BY  age;

(SELECT @curRank := 0) 部分允许变量初始化，而无需单独的 SET 命令.

The (SELECT @curRank := 0) part allows the variable initialization without requiring a separate SET command.

测试用例:

CREATE TABLE person (id int, first_name varchar(20), age int, gender char(1));

INSERT INTO person VALUES (1, 'Bob', 25, 'M');
INSERT INTO person VALUES (2, 'Jane', 20, 'F');
INSERT INTO person VALUES (3, 'Jack', 30, 'M');
INSERT INTO person VALUES (4, 'Bill', 32, 'M');
INSERT INTO person VALUES (5, 'Nick', 22, 'M');
INSERT INTO person VALUES (6, 'Kathy', 18, 'F');
INSERT INTO person VALUES (7, 'Steve', 36, 'M');
INSERT INTO person VALUES (8, 'Anne', 25, 'F');

结果:

+------------+------+--------+------+
| first_name | age  | gender | rank |
+------------+------+--------+------+
| Kathy      |   18 | F      |    1 |
| Jane       |   20 | F      |    2 |
| Nick       |   22 | M      |    3 |
| Bob        |   25 | M      |    4 |
| Anne       |   25 | F      |    5 |
| Jack       |   30 | M      |    6 |
| Bill       |   32 | M      |    7 |
| Steve      |   36 | M      |    8 |
+------------+------+--------+------+
8 rows in set (0.02 sec)

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