From 2dfaddfdf80f9b7f422d1d8d3d3aa1883ef94790 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E9=99=88=E8=83=9C=E6=9D=B0?= <2608607026@qq.com>
Date: Mon, 11 Sep 2023 05:07:59 +0000
Subject: [PATCH] 2023-05-08
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Signed-off-by: 陈胜杰 <2608607026@qq.com>
---
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+笔记：
+
+1：powerDesigner：
+
+​		第一步：创建概念模型（类似ER图）	CDM	（用户角度）
+
+​		第二步：转换成逻辑模型	LDM	（计算机角度）
+
+​		第三步：转换成物理模型	PDM	（数据库角度）
+
+​		第四步：生成DDL	
+
+2：数据库设计步骤：
+
+​		1.需求分析，了解要开发的系统的需求，明确数据和格式
+
+​		2.概念结构设计：将需求分析得到的抽象成概念模型，将ER图向关系模型转化
+
+​		3.逻辑结构设计：将概念结构转化成DBMS所支持的数据模型
+
+​		4.物理结构设计：将概念模型，转换成选定数据库管理系统需要的物理模型
+
+​		5.数据库实施：根据物理模型生成对应的DDL
+
+​		6.数据库维护
+
+```mysql
+drop table if exists` book;
+
+drop table if exists holding;
+
+drop table if exists library;
+
+drop table if exists record;
+
+drop table if exists student;
+
+/*==============================================================*/
+/* Table: book                                                  */
+/*==============================================================*/
+create table book
+(
+   bk_id                decimal not null,
+   bk_name              char(20) not null,
+   bk_author            char(10) not null,
+   ISBN                 int not null,
+   bk_date              date not null,
+   bk_sort              char(10) not null,
+   primary key (bk_id)
+);
+
+/*==============================================================*/
+/* Table: holding                                               */
+/*==============================================================*/
+create table holding
+(
+   bk_id                decimal not null,
+   lb_id                decimal not null,
+   hd_id                decimal not null,
+   primary key (bk_id, lb_id, hd_id)
+);
+
+/*==============================================================*/
+/* Table: library                                               */
+/*==============================================================*/
+create table library
+(
+   lb_id                decimal not null,
+   lb_name              char(10) not null,
+   lb_address           char(20) not null,
+   primary key (lb_id)
+);
+
+/*==============================================================*/
+/* Table: record                                                */
+/*==============================================================*/
+create table record
+(
+   bk_id                decimal not null,
+   stu_id               decimal not null,
+   rc_id                decimal not null,
+   primary key (bk_id, stu_id, rc_id)
+);
+
+/*==============================================================*/
+/* Table: student                                               */
+/*==============================================================*/
+create table student
+(
+   stu_id               decimal not null,
+   lb_id                decimal not null,
+   stu_name             char(10) not null,
+   stu_tel              varchar(11) not null,
+   stu_address          varchar(30) not null,
+   primary key (stu_id)
+);
+
+alter table holding add constraint FK_Relationship_3 foreign key (bk_id)
+      references book (bk_id) on delete restrict on update restrict;
+
+alter table holding add constraint FK_Relationship_3 foreign key (lb_id)
+      references library (lb_id) on delete restrict on update restrict;
+
+alter table record add constraint FK_Relationship_1 foreign key (bk_id)
+      references book (bk_id) on delete restrict on update restrict;
+
+alter table record add constraint FK_Relationship_1 foreign key (stu_id)
+      references student (stu_id) on delete restrict on update restrict;
+
+alter table student add constraint FK_Relationship_2 foreign key (lb_id)
+      references library (lb_id) on delete restrict on update restrict;
+```
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-- 
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