MySQL之表操作

Posted 2020-10-26 while True:just do it

一、创建表

　　1、创建新表

#语法：
create table 表名(
字段名1 类型[(宽度) 约束条件],
字段名2 类型[(宽度) 约束条件],
字段名3 类型[(宽度) 约束条件]
);

#注意：
1. 在同一张表中，字段名是不能相同
2. 宽度和约束条件可选
3. 字段名和类型是必须的

 

mysql> create table auth(
    -> id int(10) primary key auto_increment,
    -> name varchar(10) not null,
    -> age int(3),
    -> birthday datetime
    -> );
Query OK, 0 rows affected (0.36 sec)

　　2、复制表

mysql> create table auth2 select * from auth;
Query OK, 0 rows affected (0.29 sec)
Records: 0  Duplicates: 0  Warnings: 0

二、查看表

　　1、查看表结构

mysql> desc auth;
+----------+-------------+------+-----+---------+----------------+
| Field    | Type        | Null | Key | Default | Extra          |
+----------+-------------+------+-----+---------+----------------+
| id       | int(10)     | NO   | PRI | NULL    | auto_increment |
| name     | varchar(10) | NO   |     | NULL    |                |
| age      | int(3)      | YES  |     | NULL    |                |
| birthday | datetime    | YES  |     | NULL    |                |
+----------+-------------+------+-----+---------+----------------+
4 rows in set (0.02 sec)

　　2、查看表的创建信息

mysql> show create table auth;
+-------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table                                                                                                                                                                                                            |
+-------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| auth  | CREATE TABLE `auth` (
  `id` int(10) NOT NULL AUTO_INCREMENT,
  `name` varchar(10) NOT NULL,
  `age` int(3) DEFAULT NULL,
  `birthday` datetime DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 |
+-------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

　　

三、修改表

　　1、修改表名称

mysql> alter table auth2 rename auth666;
Query OK, 0 rows affected (0.10 sec)

　　2、增加表字段

mysql> alter table auth add addr char(6) not null;
Query OK, 0 rows affected (0.53 sec)
Records: 0  Duplicates: 0  Warnings: 0

　　3、修改表字段

修改表字段信息

mysql> alter table auth modify addr varchar(6) null;
Query OK, 0 rows affected (0.60 sec)
Records: 0  Duplicates: 0  Warnings: 0

　修改表字段名以及字段信息

mysql> alter table auth change addr address varchar(6);
Query OK, 0 rows affected (0.09 sec)
Records: 0  Duplicates: 0  Warnings: 0

　　4.删除表字段

mysql> alter table auth drop birthday;
Query OK, 0 rows affected (0.49 sec)
Records: 0  Duplicates: 0  Warnings: 0

四、删除表

mysql> drop table auth666;
Query OK, 0 rows affected (0.10 sec)

五、表的数据类型

http://www.cnblogs.com/fu-yong/p/8495001.html

六、表的约束

http://www.cnblogs.com/fu-yong/p/8495003.html