mysql練習之一:資料表的基本操作

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mysql練習之一:資料表的基本操作

已經學習了MySQL的各種操作,例如建立表格、新增各種限制、產看表結構、以及修改和刪除表。給出一個實戰演練,全面複習一下資料表的基本操作基礎。


案例:建立資料庫company,依照下面兩個表給出的表結構在company資料庫中建立兩個資料表offices和employees,按照操作程序完成資料表的基本操作。

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mysql練習之一:資料表的基本操作

操作过程如下:
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(1):登入MySQL。

mysql -h localhost -u root -p
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開啟windows命令列,輸入登入使用者名稱和密碼:

C:\Users\Hudie>mysql -h localhost -u root -p Enter password: ********Welcome to the MySQL monitor. Commands end with ; or \g.Your MySQL connection id is 19Server version: 8.0.16 MySQL Community Server - GPL Copyright (c) 2000, 2019, 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>_
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登入成功,可以輸入SQL語句來操作。


(2):建立資料庫company。

create database company;
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mysql> create database company;Query OK, 1 row affected (0.06 sec)
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建立成功後,在company資料庫中建立資料表,必須先選擇該資料庫。 SQL語句如下:

mysql> use company;Database changed
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(3):建立表格offices。

create table offices
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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) -> );Query OK, 0 rows affected (0.14 sec)mysql> show tables;+-------------------+| Tables_in_company |+-------------------+| offices |+-------------------+1 row in set (0.00 sec)
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(4):建立表格enployees。

create table employees
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mysql> create table employees -> ( -> employeeNumber int(11) not null primary key auto_increment, -> lastNamee 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, -> noth varchar(25), -> sex varchar(5), -> constraint office_fk foreign key(officeCode) references offices(officeCode) -> );Query OK, 0 rows affected (0.14 sec)mysql> show tables;+-------------------+| Tables_in_company |+-------------------+| employees || offices |+-------------------+2 rows in set (0.01 sec)
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建立成功,查看兩個表的結構:

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 | |+------------+-------------+------+-----+---------+-------+5 rows in set (0.06 sec)mysql> desc employees;+----------------+-------------+------+-----+---------+----------------+| Field | Type | Null | Key | Default | Extra |+----------------+-------------+------+-----+---------+----------------+| employeeNumber | int(11) | NO | PRI | NULL | auto_increment || lastNamee | 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 | || noth | varchar(25) | YES | | NULL | || sex | varchar(5) | YES | | NULL | |+----------------+-------------+------+-----+---------+----------------+9 rows in set (0.01 sec)
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(5):將表格employees的mobile欄位修改到officeCode欄位後面。

alter table employees modify mobile varchar(25) after officeCode;
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mysql> alter table employees modify mobile varchar(25) after officeCode;Query OK, 0 rows affected (0.18 sec)Records: 0 Duplicates: 0 Warnings: 0mysql> desc employees;+----------------+-------------+------+-----+---------+----------------+| Field | Type | Null | Key | Default | Extra |+----------------+-------------+------+-----+---------+----------------+| employeeNumber | int(11) | NO | PRI | NULL | auto_increment || lastNamee | 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 | || noth | varchar(25) | YES | | NULL | || sex | varchar(5) | YES | | NULL | |+----------------+-------------+------+-----+---------+----------------+9 rows in set (0.01 sec)
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(6):將表格employees的birth欄位改名為employee_birth。

alter table employees change birth employee_birth datetime;
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mysql> alter table employees change birth employee_birth datetime;Query OK, 0 rows affected (0.03 sec)Records: 0 Duplicates: 0 Warnings: 0mysql> desc employees;+----------------+-------------+------+-----+---------+----------------+| Field | Type | Null | Key | Default | Extra |+----------------+-------------+------+-----+---------+----------------+| employeeNumber | int(11) | NO | PRI | NULL | auto_increment || lastNamee | 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 | || noth | varchar(25) | YES | | NULL | || sex | varchar(5) | YES | | NULL | |+----------------+-------------+------+-----+---------+----------------+9 rows in set (0.00 sec)
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(7):修改sex字段,設定資料類型為char(1),非空約束。

alter table employees modify sex char(1) not null;
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mysql> alter table employees modify sex char(1) not null;Query OK, 0 rows affected (0.20 sec)Records: 0 Duplicates: 0 Warnings: 0mysql> desc employees;+----------------+-------------+------+-----+---------+----------------+| Field | Type | Null | Key | Default | Extra |+----------------+-------------+------+-----+---------+----------------+| employeeNumber | int(11) | NO | PRI | NULL | auto_increment || lastNamee | 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 | || noth | varchar(25) | YES | | NULL | || sex | char(1) | NO | | NULL | |+----------------+-------------+------+-----+---------+----------------+9 rows in set (0.01 sec)
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(8):刪除欄位noth。

alter table employees drop noth;
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mysql> alter table employees drop noth;Query OK, 0 rows affected (0.15 sec)Records: 0 Duplicates: 0 Warnings: 0mysql> desc employees;+----------------+-------------+------+-----+---------+----------------+| Field | Type | Null | Key | Default | Extra |+----------------+-------------+------+-----+---------+----------------+| employeeNumber | int(11) | NO | PRI | NULL | auto_increment || lastNamee | 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 | |+----------------+-------------+------+-----+---------+----------------+8 rows in set (0.01 sec)
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(9):增加欄位名稱favoriate_activity,資料型別為varchar(100)

alter table employees add favoriate_activity varchar(100);
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mysql> alter table employees add favoriate_activity varchar(100);Query OK, 0 rows affected (0.09 sec)Records: 0 Duplicates: 0 Warnings: 0mysql> desc employees;+--------------------+--------------+------+-----+---------+----------------+| Field | Type | Null | Key | Default | Extra |+--------------------+--------------+------+-----+---------+----------------+| employeeNumber | int(11) | NO | PRI | NULL | auto_increment || lastNamee | 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 | |+--------------------+--------------+------+-----+---------+----------------+9 rows in set (0.00 sec)
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(10 ):刪除主表offices

①刪除表的外鍵限制:alter table employees drop foreign key office_fk;
②刪除表offices:drop table offices;

mysql> alter table employees drop foreign key office_fk;Query OK, 0 rows affected (0.03 sec)Records: 0 Duplicates: 0 Warnings: 0mysql> drop table offices;Query OK, 0 rows affected (0.03 sec)mysql> show tables;+-------------------+| Tables_in_company |+-------------------+| employees |+-------------------+1 row in set (0.06 sec)
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(11):修改表格employees儲存引擎為MyISAM。

alter table employees ENGINE=MyISAM;
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mysql> alter table employees ENGINE=MyISAM;Query OK, 0 rows affected (0.17 sec)Records: 0 Duplicates: 0 Warnings: 0mysql> show create table employees \G*************************** 1. row *************************** Table: employeesCreate Table: CREATE TABLE `employees` ( `employeeNumber` int(11) NOT NULL AUTO_INCREMENT, `lastNamee` 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=utf8mb4 COLLATE=utf8mb4_0900_ai_ci1 row in set (0.00 sec)
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(12)將表employees名稱修改為employees_info。

alter table employees rename employees_info;
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mysql> alter table employees rename employees_info;Query OK, 0 rows affected (0.07 sec)mysql> show tables;+-------------------+| Tables_in_company |+-------------------+| employees_info |+-------------------+1 row in set (0.00 sec)
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