語法規則
| SELECT column_name(s)FROM table_name1INNER JOIN table_name2 ON table_name1.column_name=table_name2.column_name |
先創建兩個表，1.用戶，2.用戶類別
用戶表
| 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; |
用戶類別表
| CREATE TABLE `userkind` ( `id` int(32) NOT NULL AUTO_INCREMENT, `kindname` varchar(16) NOT NULL, PRIMARY KEY (`id`)) ENGINE=MyISAM DEFAULT CHARSET=utf8; |
插入一些數據到user表
INSERT INTO `user` VALUES (1,'小明',1),(2,'小紅',1),(3,'涵涵',2);插入一些數據到 userkind表
INSERT INTO `userkind` VALUES (1,'普通會員'),(2,'VIP會員');
如圖：
下面是控制臺的查詢例子：
| Enter password: ****Welcome to the MySQL monitor. Commands end with ; or /g.Your MySQL connection id is 2Server 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 itsaffiliates. Other names may be trademarks of their respectiveowners.Type 'help;' or '/h' for help. Type '/c' to clear the current input statement.mysql> use join;Database changedmysql> select * from `user`;+----+------+--------+| id | name | kindid |+----+------+--------+| 1 | 小明 | 1 || 2 | 小紅 | 1 || 3 | 涵涵 | 2 |+----+------+--------+3 rows in set (0.00 sec)mysql> select * from `userkind`;+----+----------+| id | kindname |+----+----------+| 1 | 普通會員 || 2 | VIP會員 |+----+----------+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 | 普通會員 || 2 | 小紅 | 1 | 1 | 普通會員 || 3 | 涵涵 | 2 | 2 | VIP會員 |+----+------+--------+----+----------+3 rows in set (0.02 sec)mysql> select `id` as `用戶ID`,`name` as `用戶名`,`kindname` as `用戶類別` from`user` inner join `userkind` where user.kindid=userkind.id;ERROR 1052 (23000): Column 'id' in field list is ambiguousmysql> select `user`.`id` as `用戶ID`,`name` as `用戶名`,`kindname` as `用戶類別` from -> `user` inner join `userkind` where `user`.`kindid`=`userkind`.`id`;+--------+--------+----------+| 用戶ID | 用戶名 | 用戶類別 |+--------+--------+----------+| 1 | 小明 | 普通會員 || 2 | 小紅 | 普通會員 || 3 | 涵涵 | VIP會員 |+--------+--------+----------+3 rows in set (0.00 sec)mysql> select `user`.`id` as `用戶ID`,`name` as `用戶名`,`kindname` as `用戶類別` from `user` inner join `userkind` on `user`.`kindid`=`userkind`.`id`;+--------+--------+----------+| 用戶ID | 用戶名 | 用戶類別 |+--------+--------+----------+| 1 | 小明 | 普通會員 || 2 | 小紅 | 普通會員 || 3 | 涵涵 | VIP會員 |+--------+--------+----------+3 rows in set (0.00 sec)mysql> |
