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【实验1 数据库基本表定义及修改】

前行的跋涉者 2022-04-20 阅读 47
mysql

一、课程名称: 数据库原理

二、实验名称:实验1 数据库基本表定义及修改

三、实验地点与实验环境:

实验环境: 装有MySQLPC机。

四、实验内容

1、创建数据库

创建名为“books_db”的数据库。

 2、建立基本表

MySQL命令行客户端中,使用SQL语句在“books_db”数据库中建立以下四个表。表结构如下:(注意:在创建表之前,需使用use命令打开“books_db”数据库)

 3、修改基本表(使用SQL语句)

1)给读者表增加一个“备注”字段,类型为varchar(150)

2)将“备注”字段的类型修改为varchar(200)

3)删除“备注”字段;

4)将图书表中的“库存”字段类型改为smallint

SQL语句:

  1. create database books_db DEFAULT CHARACTER SET utf8mb4;
  2. show databases;
  3. use books_db;

4.CREATE TABLE book (        

           book_number   char(10) PRIMARY KEY,                

            category  varchar(12), 

            book_name    varchar(30) NOT NULL,

            publisher   char(30) NOT NULL,

           author char(10),

           price numeric(5,2),

           book_total int NOT NULL,

           inventory int NOT NULL

           );

5. CREATE TABLE reader(

       reader_number CHAR(10) PRIMARY KEY,

       name varchar(8) not null,

       department char(20) ,

       gender char(2) not null,

       telephone char(15) );

6. CREATE TABLE borrow_book(

       reader_number CHAR(10) not null,

       book_number char(10) not null,

       borrow_time datetime not null,

       PRIMARY KEY(reader_number,book_number),

       foreign KEY(book_number) references book (book_number),   

       foreign KEY(reader_number) references reader(reader_number)

);

7. CREATE TABLE return_book(

       reader_number CHAR(10) not null,

       book_number char(10) not null,

       retrun_time datetime not null,

       PRIMARY KEY(reader_number,book_number),

       foreign KEY(book_number) references book (book_number),   

       foreign KEY(reader_number) references reader(reader_number)

);

8. ALTER TABLE reader ADD (note varchar(150));

9.ALTER TABLE reader MODIFY note varchar(200);

10. ALTER TABLE reader DROP COLUMN  note;

11. ALTER TABLE book MODIFY  inventory smallint;

五、实验步骤、结果或结论:

1. create database books_db DEFAULT CHARACTER SET utf8mb4;

2.建立基本表

(1)图书表,表名:book

CREATE TABLE book (        

           book_number   char(10) PRIMARY KEY,                

            category  varchar(12), 

            book_name    varchar(30) NOT NULL,

            publisher   char(30) NOT NULL,

           author char(10),

           price numeric(5,2),

           book_total int NOT NULL,

           inventory int NOT NULL

           );

(2)读者表, 表名:reader

CREATE TABLE reader(

       reader_number CHAR(10) PRIMARY KEY,

       name varchar(8) not null,

       department char(20) ,

       gender char(2) not null,

       telephone char(15) );

(3)借书表, 表名:borrow_book

CREATE TABLE borrow_book(

       reader_number CHAR(10) not null,

       book_number char(10) not null,

       borrow_time datetime not null,

       PRIMARY KEY(reader_number,book_number),

       foreign KEY(book_number) references book (book_number),   

       foreign KEY(reader_number) references reader(reader_number)

);

4. CREATE TABLE return_book(

       reader_number CHAR(10) not null,

       book_number char(10) not null,

       retrun_time datetime not null,

       PRIMARY KEY(reader_number,book_number),

       foreign KEY(book_number) references book (book_number),   

       foreign KEY(reader_number) references reader(reader_number)

);

3、修改基本表(使用SQL语句)

1)给读者表增加一个“备注”字段,类型为varchar(150)

ALTER TABLE reader ADD (note varchar(150));

2)将“备注”字段的类型修改为varchar(200)

ALTER TABLE reader MODIFY note varchar(200);

3)删除“备注”字段;

ALTER TABLE reader DROP COLUMN  note;

4)将图书表中的“库存”字段类型改为smallint

ALTER TABLE book MODIFY  inventory smallint;

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