Chapter 3 Entity Relationship Model

DFC2033

Course Learning Outcome �  CLO1: Apply the fundamentals concepts of database

management and relational data model to create a database based on an organization’s requirements. (C3, PLO1)

�  CLO2: Develop a database using a concurrency control and data recovery technique based on Database Management System (DBMS). (P3, C3, PLO2, PLO1)

Learning Outcome �  Apply Entity Relationship Diagrams (ERD) in database

development �  Define the three basic elements of ERD: entity types, relationship,

attributes and keys. �  Use Chen’s Model to draw ERD �  Use Crow’s Foot notations to draw ERD. �  Design E-R model based on a given scenario. �  Describe the basic conversion rules to convert ERD into relational

tables: a. One to one relationship b. One to many relationship c. Many to many relationship

�  Apply the conversion rules to convert a given ERD into relational tables

ERD: Crows Foot Model

Crows Foot Notation

Crows Foot Notation

ERD: Chen’s Model

1

Exercise A company database needs to store information about employees (identified by ssn, with salary and phone as attributes), departments (identified by dno, with dname and budget as attributes), and children of employees (with name and age as attributes).

Analyze the problem/case �  A company database needs to store information about

employees (identified by ssn, with salary and phone as attributes), departments (identified by dno, with dname and budget as attributes), and children of employees (with name and age as attributes).

�  Employees work in departments; a child must be identified uniquely by name when the parent (who is an employee; assume that only one parent works for the company) is known.

� Draw an ER diagram that captures this information.

Apply the conversion rules to convert a given ERD into relational tables

Departments

Child

Employees

name age

phone ssn

salary

Dependent

budget dno

dname

Works_In