Conceptual model design of the 2022 database of tyut Taiyuan University of Technology

Question 2

A description of a database is given in the question , Let's draw the database E-R chart , And indicate the attribute on the figure 、 The type of connection

（“ And indicate the attribute on the figure 、 The type of connection ” This sentence appears in the exam , Just treat him as if he didn't ; Because attributes are ellipses , Type is one-on-one , One to many , Many to many , These two things are paintings E-R Pictures must be drawn , In fact, from another perspective ,ER The attributes of a graph are divided into composite attributes 、 Multi valued attribute 、 Derived properties 、 Optional attribute , Contact properties , But we don't test so deep ）

Talking about ： This question should be a free question , I won't go into details , I believe everyone will , According to the requirements of the topic , Like high school Chinese reading , Find the entities in the topic （ Rectangle ）、 Draw the properties next to the rectangle （ The ellipse ）, Find out the relationship （ The diamond / The predicate in the question ） Then use according to the meaning of the topic 1、n、m Just connect , It should be noted that you should not use both adjacent many to many lines n Express , You have to use one n, One use m

Attach two examples to practice by yourself , If not, go back to the blog “ Question 1 E-R Graph to relational model ”, If you can't make a comment yet

example 1. Books in a library are stored in multiple libraries by category , For readers to borrow . There are several administrators in each library （ These administrators no longer manage other stacks ）. Please design a database to store relevant information . among :

（1） The properties of the library include the library number 、 Location 、 Area etc. , The attributes of books include book numbers 、 Title 、 Publishing house, etc , The attributes of readers include reader number 、 full name 、 Unit, etc , The attributes of the administrator include employee number 、 Employee name and other attributes ; Please specify other properties by yourself .（2） The attributes that describe the borrowing relationship include lending date and return date

Try to draw the Library 、 The book 、 readers 、 Administrators and their contacts E-R chart （ It is required to indicate the relevant attributes and contact types ）, And transform it into a relational pattern （ It is required to indicate the main code ）.

Explain ：

1. Library management database

  （1） Library management database E-R The graph is as follows ：

  （2） The transformation to relational mode is as follows ：

Library （ Library number , Address , area ）

workers （ Employee number , full name , Age , Library number ）

The book （ Book number , Title , author , Press. , Library number ）

   readers （ Reader number , full name , Company ）

   Borrow （ Reader number , Book number , Borrowing date , Return date ）

2. Suppose a department's database contains the following information ：

Employee information ： Employee number 、 full name 、 Address and department .

Department Information ： Department name 、 Manager's name 、 Telephone .

Product information ： Product number 、 Product name 、 Price 、 model .

Manufacturer's information ： Factory name 、 site of a factory 、 Fax .

In addition, it also includes information about the products sold by the Department and the products produced by the manufacturer .

Try to draw this database E-R chart （ It is required to indicate the relevant attributes and contact types ）, And transform it into a relational pattern （ It is required to indicate the main code ）.

Explain ：

（1） database E-R The graph is as follows ：

（2） The transformation to relational mode is as follows ：

workers （ Employee number , full name , Address , Department name ）

department （ Department name , The manager , Telephone ）

product （ Product number , Product name , model , The unit price ）

   sales （ Department name , Product number ）

Manufacturer （ Factory name , site of a factory , Fax ）

   production （ Product number , Factory name ）