Navicat premium导出E-R图

大学数据库模式

下面以数据库系统概念第6版的大学数据库模式作为示例
创建一个数据库名为:

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university

然后进入这个数据库,执行如下建表命令:

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create table classroom
(building varchar(15),
room_number varchar(7),
capacity numeric(4,0),
primary key (building, room_number)
);
create table department
(dept_name varchar(20),
building varchar(15),
budget numeric(12,2) check (budget > 0),
primary key (dept_name)
);
create table course
(course_id varchar(8),
title varchar(50),
dept_name varchar(20),
credits numeric(2,0) check (credits > 0),
primary key (course_id),
foreign key (dept_name) references department(dept_name)
on delete set null
);
create table instructor
(ID varchar(5),
name varchar(20) not null,
dept_name varchar(20),
salary numeric(8,2) check (salary > 29000),
primary key (ID),
foreign key (dept_name) references department(dept_name)
on delete set null
);
create table section
(course_id varchar(8),
sec_id varchar(8),
semester varchar(6)
check (semester in ('Fall', 'Winter', 'Spring', 'Summer')),
year numeric(4,0) check (year > 1701 and year < 2100),
building varchar(15),
room_number varchar(7),
time_slot_id varchar(4),
primary key (course_id, sec_id, semester, year),
foreign key (course_id) references course(course_id)
on delete cascade,
foreign key (building, room_number) references classroom(building, room_number)
on delete set null
);
create table teaches
(ID varchar(5),
course_id varchar(8),
sec_id varchar(8),
semester varchar(6),
year numeric(4,0),
primary key (ID, course_id, sec_id, semester, year),
foreign key (course_id,sec_id, semester, year) references section(course_id,sec_id, semester, year)
on delete cascade,
foreign key (ID) references instructor(ID)
on delete cascade
);
create table student
(ID varchar(5),
name varchar(20) not null,
dept_name varchar(20),
tot_cred numeric(3,0) check (tot_cred >= 0),
primary key (ID),
foreign key (dept_name) references department(dept_name)
on delete set null
);
create table takes
(ID varchar(5),
course_id varchar(8),
sec_id varchar(8),
semester varchar(6),
year numeric(4,0),
grade varchar(2),
primary key (ID, course_id, sec_id, semester, year),
foreign key (course_id,sec_id, semester, year) references section(course_id,sec_id, semester, year)
on delete cascade,
foreign key (ID) references student(ID)
on delete cascade
);
create table advisor
(s_ID varchar(5),
i_ID varchar(5),
primary key (s_ID),
foreign key (i_ID) references instructor (ID)
on delete set null,
foreign key (s_ID) references student (ID)
on delete cascade
);
create table time_slot
(time_slot_id varchar(4),
day varchar(1),
start_hr numeric(2) check (start_hr >= 0 and start_hr < 24),
start_min numeric(2) check (start_min >= 0 and start_min < 60),
end_hr numeric(2) check (end_hr >= 0 and end_hr < 24),
end_min numeric(2) check (end_min >= 0 and end_min < 60),
primary key (time_slot_id, day, start_hr, start_min)
);
create table prereq
(course_id varchar(8),
prereq_id varchar(8),
primary key (course_id, prereq_id),
foreign key (course_id) references course(course_id)
on delete cascade,
foreign key (prereq_id) references course(course_id)
);

逆向数据库到模型

逆向数据库到模型可以将mysql中创建好的表转成E-R图。
步骤如下图所示:
图片
这样就得到E-R图了,如下所示:
图片

切换E-R图 表示方式

图片

UML格式的E-R图如下所示

图片