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+### 软件：PowerDesigner使用
+
+#### 第一步：创建概念模型（类似ER图），以用户的角度。简称 CDM
+
+#### 第二步：将转概念模型换成逻辑模型，以计算机的角度。简称 LDM
+
+#### 第三步：将逻辑模型转换成物理模型，以数据库的角度。简称 PDM
+
+#### 第四步：生成DDL（生成数据库代码）
+
+![](E:\所有仓库\数据库高级\database-advanced\04 李明健\图书管理系统E-R图.png)
+
+###  图书管理系统
+
+~~~ mysql
+#创建数据库并选择
+create database lib charset utf8;
+use lib;
+
+#创建书架表
+create table bookshelf(
+	bs_id int primary key,
+	bs_type varchar(5)
+);
+#插入数据
+insert into bookshelf values
+(1,"文学类"),
+(2,"数理类"),
+(3,"人文科学类");
+
+#创建图书信息表
+create table book_info(
+	book_id varchar(3) primary key,
+	book_name varchar(15) not null,
+	bs_id int,
+	foreign key (bs_id) references bookshelf(bs_id)
+);
+#插入数据
+insert into book_info values
+(101,"朝花夕拾",1),
+(102,"高等数学",2),
+(103,"MySQL从入门到起飞",2),
+(104,"红楼梦",1),
+(105,"物种起源",3);
+
+#创建图书管理员表
+create table librarian(
+	lr_id varchar(3) primary key,
+	lr_name varchar(5) not null,
+	bs_id int,
+	foreign key (bs_id) references bookshelf(bs_id)
+);
+#插入数据
+insert into librarian values
+(001,"张三",1),
+(002,"李四",2),
+(003,"王五",3);
+
+#创建学生信息表
+create table student(
+	stu_id varchar(10) primary key,
+	stu_name varchar(5) not null,
+	sex varchar(1) not null,
+	college varchar(10) not null
+);
+#插入数据
+insert into student values
+("2244310201","田霜笑","女","软件工程学院"),
+("2244310202","丰博嘉","男","软件工程学院"),
+("2244310203","阳文康","男","软件工程学院"),
+("2244310204","孙曼蓉","女","软件工程学院");
+
+#创建借阅表
+create table borrow(
+	bo_time varchar(10) not null,	#借阅时间
+	re_time varchar(10) not null,	#需归还时间
+	book_id varchar(3),			   #图书编号
+	foreign key (book_id) references book_info(book_id),
+	stu_id varchar(10) not null,  #学号
+	foreign key (stu_id) references student(stu_id)
+);
+#插入数据
+insert into borrow values
+("2023-09-08","2023-10-08",101,"2244310201"),
+("2023-08-15","2023-09-15",103,"2244310201"),
+("2023-09-20","2023-10-20",102,"2244310202"),
+("2023-09-11","2023-10-11",105,"2244310203"),
+("2023-09-11","2023-10-11",104,"2244310204");
+
+#创建借阅表
+create table `return`(
+	bo_time varchar(10) not null,	#借阅时间
+	re_time varchar(10) not null,	#归还时间
+	book_id varchar(3),			   #图书编号
+	foreign key (book_id) references book_info(book_id),
+	stu_id varchar(10) not null,  #学号
+	foreign key (stu_id) references student(stu_id)
+);
+#插入数据
+insert into `return` values
+("2023-09-08","2023-10-02",101,"2244310201"),
+("2023-08-15","2023-09-16",103,"2244310201"),
+("2023-09-20","2023-10-10",102,"2244310202"),
+("2023-09-11","2023-10-15",105,"2244310203"),
+("2023-09-11","2023-10-01",104,"2244310204");
+
+#查询
+select * from student s,borrow br,bookshelf bs,book_info bi where s.stu_id=br.stu_id and bi.book_id=br.book_id and bs.bs_id=bi.bs_id;
+
+~~~
+
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