一、创建数据库
mysql> create database company; mysql> use company;
二、创建表
1. 创建表offices
mysql> create table offices
-> (
-> officeCode int(10) NOT NULL UNIQUE,
-> city varchar(50) NOT NULL,
-> address varchar(50) NOT NULL,
-> country varchar(50) NOT NULL,
-> postalCode varchar(15) NOT NULL,
-> PRIMARY KEY (officeCode)
-> );
2. 创建表employees
mysql> create table employees
-> (
-> employeeNumber int(11) NOT NULL PRIMARY KEY AUTO_INCREMENT,
-> lastName VARCHAR(50) NOT NULL,
-> firstName VARCHAR(50) NOT NULL,
-> mobile VARCHAR(25) NOT NULL,
-> officeCode int(10) NOT NULL,
-> jobTitle VARCHAR(50) NOT NULL,
-> birth DATETIME,
-> note VARCHAR(255),
-> sex VARCHAR(5),
-> CONSTRAINT office_fk FOREIGN KEY (officeCode) REFERENCES offices(officeCode)
-> );
3. 查看数据库已创建的表
mysql> show tables; +-------------------+ | Tables_in_company | +-------------------+ | employees | | offices | +-------------------+
mysql> desc offices; +------------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +------------+-------------+------+-----+---------+-------+ | officeCode | int(10) | NO | PRI | NULL | | | city | varchar(50) | NO | | NULL | | | address | varchar(50) | NO | | NULL | | | country | varchar(50) | NO | | NULL | | | postalCode | varchar(15) | NO | | NULL | | +------------+-------------+------+-----+---------+-------+
mysql> desc employees; +----------------+--------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +----------------+--------------+------+-----+---------+----------------+ | employeeNumber | int(11) | NO | PRI | NULL | auto_increment | | lastName | varchar(50) | NO | | NULL | | | firstName | varchar(50) | NO | | NULL | | | mobile | varchar(25) | NO | | NULL | | | officeCode | int(10) | NO | MUL | NULL | | | jobTitle | varchar(50) | NO | | NULL | | | birth | datetime | YES | | NULL | | | note | varchar(255) | YES | | NULL | | | sex | varchar(5) | YES | | NULL | | +----------------+--------------+------+-----+---------+----------------+
三、表的基本操作
1. 将表employees的mobile字段修改到officeCode字段后面
mysql> alter table employees MODIFY mobile varchar(25) after officeCode; mysql> desc employees; +----------------+--------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +----------------+--------------+------+-----+---------+----------------+ | employeeNumber | int(11) | NO | PRI | NULL | auto_increment | | lastName | varchar(50) | NO | | NULL | | | firstName | varchar(50) | NO | | NULL | | | officeCode | int(10) | NO | MUL | NULL | | | mobile | varchar(25) | YES | | NULL | | | jobTitle | varchar(50) | NO | | NULL | | | birth | datetime | YES | | NULL | | | note | varchar(255) | YES | | NULL | | | sex | varchar(5) | YES | | NULL | | +----------------+--------------+------+-----+---------+----------------+
2. 将表employees的birth字段改名为employee_birth
mysql> alter table employees CHANGE birth employee_birth DATETIME; mysql> desc employees; +----------------+--------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +----------------+--------------+------+-----+---------+----------------+ | employeeNumber | int(11) | NO | PRI | NULL | auto_increment | | lastName | varchar(50) | NO | | NULL | | | firstName | varchar(50) | NO | | NULL | | | officeCode | int(10) | NO | MUL | NULL | | | mobile | varchar(25) | YES | | NULL | | | jobTitle | varchar(50) | NO | | NULL | | | employee_birth | datetime | YES | | NULL | | | note | varchar(255) | YES | | NULL | | | sex | varchar(5) | YES | | NULL | | +----------------+--------------+------+-----+---------+----------------+
3. 修改sex字段，数据类型为CHAR(1),非空约束
mysql> alter table employees MODIFY sex CHAR(1) NOT NULL; mysql> desc employees; +----------------+--------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +----------------+--------------+------+-----+---------+----------------+ | employeeNumber | int(11) | NO | PRI | NULL | auto_increment | | lastName | varchar(50) | NO | | NULL | | | firstName | varchar(50) | NO | | NULL | | | officeCode | int(10) | NO | MUL | NULL | | | mobile | varchar(25) | YES | | NULL | | | jobTitle | varchar(50) | NO | | NULL | | | employee_birth | datetime | YES | | NULL | | | note | varchar(255) | YES | | NULL | | | sex | char(1) | NO | | NULL | | +----------------+--------------+------+-----+---------+----------------+
4. 删除字段note
mysql> alter table employees DROP note; mysql> desc employees; +----------------+-------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +----------------+-------------+------+-----+---------+----------------+ | employeeNumber | int(11) | NO | PRI | NULL | auto_increment | | lastName | varchar(50) | NO | | NULL | | | firstName | varchar(50) | NO | | NULL | | | officeCode | int(10) | NO | MUL | NULL | | | mobile | varchar(25) | YES | | NULL | | | jobTitle | varchar(50) | NO | | NULL | | | employee_birth | datetime | YES | | NULL | | | sex | char(1) | NO | | NULL | | +----------------+-------------+------+-----+---------+----------------+
5. 增加字段名favoriate_activity, 数据类型为VARCHAR(100)
mysql> alter table employees ADD favoriate_activity varchar(100); mysql> desc employees; +--------------------+--------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +--------------------+--------------+------+-----+---------+----------------+ | employeeNumber | int(11) | NO | PRI | NULL | auto_increment | | lastName | varchar(50) | NO | | NULL | | | firstName | varchar(50) | NO | | NULL | | | officeCode | int(10) | NO | MUL | NULL | | | mobile | varchar(25) | YES | | NULL | | | jobTitle | varchar(50) | NO | | NULL | | | employee_birth | datetime | YES | | NULL | | | sex | char(1) | NO | | NULL | | | favoriate_activity | varchar(100) | YES | | NULL | | +--------------------+--------------+------+-----+---------+----------------+
6. 删除表offices
1) 创建表时设置了表的外键，所以不能直接删除
mysql> drop table offices; ERROR 1217 (23000): Cannot delete or update a parent row: a foreign key constraint fails
2) 删除employees表的外键约束
mysql> alter table employees drop foreign key office_fk;
3) 删除offices表
mysql> drop table offices; Query OK, 0 rows affected (0.03 sec)
mysql> show tables; +-------------------+ | Tables_in_company | +-------------------+ | employees | +-------------------+
7. 修改employees表的存储引擎为MyISAM
mysql> alter table employees ENGINE=MyISAM;
Query OK, 0 rows affected (0.12 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> show create table employees\G;
*************************** 1. row ***************************
Table: employees
Create Table: CREATE TABLE `employees` (
`employeeNumber` int(11) NOT NULL AUTO_INCREMENT,
`lastName` varchar(50) NOT NULL,
`firstName` varchar(50) NOT NULL,
`officeCode` int(10) NOT NULL,
`mobile` varchar(25) DEFAULT NULL,
`jobTitle` varchar(50) NOT NULL,
`employee_birth` datetime DEFAULT NULL,
`sex` char(1) NOT NULL,
`favoriate_activity` varchar(100) DEFAULT NULL,
PRIMARY KEY (`employeeNumber`),
KEY `office_fk` (`officeCode`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1
1 row in set (0.01 sec)
8. 将表employees表名改为employees_info
mysql> alter table employees rename employees_info; Query OK, 0 rows affected (0.00 sec) mysql> show tables; +-------------------+ | Tables_in_company | +-------------------+ | employees_info | +-------------------+ 1 row in set (0.00 sec)
如果您们在尝试的过程中遇到什么问题或者我的代码有错误的地方，请给予指正，非常感谢！
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