MYSQL数据库Mysql inner join on的用法实例(必看)

《MYSQL数据库Mysql inner join on的用法实例(必看)》要点：
本文介绍了MYSQL数据库Mysql inner join on的用法实例(必看)，希望对您有用。如果有疑问，可以联系我们。

MYSQL入门语法规则

MYSQL入门
SELECT column_name(s)
FROM table_name1
INNER JOIN table_name2 
ON table_name1.column_name=table_name2.column_name

MYSQL入门先创建两个表,1.用户,2.用户类别

MYSQL入门用户表

MYSQL入门
CREATE TABLE `user` (
 `id` int(32) NOT NULL AUTO_INCREMENT,`name` varchar(16) NOT NULL,`kindid` int(32) NOT NULL,PRIMARY KEY (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;

MYSQL入门用户类别表

MYSQL入门
CREATE TABLE `userkind` (
 `id` int(32) NOT NULL AUTO_INCREMENT,`kindname` varchar(16) NOT NULL,PRIMARY KEY (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;

MYSQL入门插入一些数据到user表

MYSQL入门INSERT INTO `user` VALUES (1,'小明',1),(2,'小红',(3,'涵涵',2);插入一些数据到 userkind表

MYSQL入门INSERT INTO `userkind` VALUES (1,'普通会员'),'VIP会员');

MYSQL入门如图：

MYSQL入门

MYSQL入门下面是控制台的查询例子：

MYSQL入门
Enter password: ****
Welcome to the MySQL monitor. Commands end with ; or g.
Your MySQL connection id is 2
Server version: 5.5.40 MySQL Community Server (GPL)
Copyright (c) 2000,2014,Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or 'h' for help. Type 'c' to clear the current input statement.
mysql> use join;
Database changed
mysql> select * from `user`;
+----+------+--------+
| id | name | kindid |
+----+------+--------+
| 1 | 小明 |   1 |
| 2 | 小红 |   1 |
| 3 | 涵涵 |   2 |
+----+------+--------+
3 rows in set (0.00 sec)
mysql> select * from `userkind`;
+----+----------+
| id | kindname |
+----+----------+
| 1 | 普通会员 |
| 2 | VIP会员 |
+----+----------+
2 rows in set (0.00 sec)
mysql> select * from `user` inner join `userkind` on user.kindid=userkind.id;
+----+------+--------+----+----------+
| id | name | kindid | id | kindname |
+----+------+--------+----+----------+
| 1 | 小明 |   1 | 1 | 普通会员 |
| 2 | 小红 |   1 | 1 | 普通会员 |
| 3 | 涵涵 |   2 | 2 | VIP会员 |
+----+------+--------+----+----------+
3 rows in set (0.02 sec)
mysql> select `id` as `用户ID`,`name` as `用户名`,`kindname` as `用户类别` from
`user` inner join `userkind` where user.kindid=userkind.id;
ERROR 1052 (23000): Column 'id' in field list is ambiguous
mysql> select `user`.`id` as `用户ID`,`kindname` as `用户类别
` from
  -> `user` inner join `userkind` where `user`.`kindid`=`userkind`.`id`;
+--------+--------+----------+
| 用户ID | 用户名 | 用户类别 |
+--------+--------+----------+
|   1 | 小明  | 普通会员 |
|   2 | 小红  | 普通会员 |
|   3 | 涵涵  | VIP会员 |
+--------+--------+----------+
3 rows in set (0.00 sec)
mysql> select `user`.`id` as `用户ID`,`kindname` as `用户类别
` from `user` inner join `userkind` on `user`.`kindid`=`userkind`.`id`;
+--------+--------+----------+
| 用户ID | 用户名 | 用户类别 |
+--------+--------+----------+
|   1 | 小明  | 普通会员 |
|   2 | 小红  | 普通会员 |
|   3 | 涵涵  | VIP会员 |
+--------+--------+----------+
3 rows in set (0.00 sec)
mysql>

MYSQL入门需要注意的是： 这里的on 基本等价于where(本人感觉)

MYSQL入门当 column (字段) 两个表都有 却分不清时,需要用`表名`.`字段名` 进行分辨.

MYSQL入门as就是取别名了.看上面例子就知道!

MYSQL入门以上这篇Mysql inner join on的用法实例(必看)就是小编分享给大家的全部内容了,希望能给大家一个参考,也希望大家多多支持编程之家PHP.

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