MySQL數據表的基本操作三：綜合示例
來源：程序員人生 發布時間：2014-10-08 08:00:01 閱讀次數：8166次
一、創建數據庫
mysql> create database company;
mysql> use company;
二、創建表
1. 創建表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. 創建表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. 查看數據庫已創建的表
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. 將表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. 將表employees的birth字段改名為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，數據類型為CHAR(1),非空約束
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. 刪除字段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, 數據類型為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. 刪除表offices
1) 創建表時設置了表的外鍵，所以不能直接刪除
mysql> drop table offices;
ERROR 1217 (23000): Cannot delete or update a parent row: a foreign key constraint fails
2) 刪除employees表的外鍵約束
mysql> alter table employees drop foreign key office_fk;
3) 刪除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表的存儲引擎為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 employeesG;
*************************** 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. 將表employees表名改為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)
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