Mysql inner join on的用法实例(必看)
发布于 2017-06-09 04:15:58 | 182 次阅读 | 评论: 0 | 来源: 网友投递
Mysql关系型数据库管理系统
MySQL是一个开放源码的小型关联式数据库管理系统，开发者为瑞典MySQL AB公司。MySQL被广泛地应用在Internet上的中小型网站中。由于其体积小、速度快、总体拥有成本低，尤其是开放源码这一特点，许多中小型网站为了降低网站总体拥有成本而选择了MySQL作为网站数据库。
下面小编就为大家带来一篇Mysql inner join on的用法实例(必看)。小编觉得挺不错的，现在就分享给大家，也给大家做个参考。一起跟随小编过来看看吧
语法规则
SELECT column_name(s)
FROM table_name1
INNER JOIN table_name2
ON table_name1.column_name=table_name2.column_name
先创建两个表，1.用户，2.用户类别
用户表
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;
用户类别表
CREATE TABLE `userkind` (
`id` int(32) NOT NULL AUTO_INCREMENT,
`kindname` varchar(16) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;
插入一些数据到user表
INSERT INTO `user` VALUES (1,'小明',1),(2,'小红',1),(3,'涵涵',2);插入一些数据到 userkind表
INSERT INTO `userkind` VALUES (1,'普通会员'),(2,'VIP会员');
如图：
下面是控制台的查询例子：
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`,`name` as `用户名`,`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`,`name` as `用户名`,`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>
需要注意的是： 这里的on 基本等价于where(本人感觉)
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。
as就是取别名了。看上面例子就知道！
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PHPERZ。
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