Lecture 03

Entity-Relationship Diagram

Chapter Outline

Overview of Database Design Process

Overview of Database Design Process

Example COMPANY Database

Example COMPANY Database(Contd.)

ER Model Concepts

Types of Attributes (1)

Types of Attributes (2)

Example of a composite attribute

Entity Types and Key Attributes (1)

Entity Types and Key Attributes (2)

Displaying an Entity type

Entity Type CAR with two keys and acorresponding Entity Set

Entity Set

Initial Design of Entity Types for theCOMPANY Database Schema

Initial Design of Entity Types:EMPLOYEE, DEPARTMENT, PROJECT,

DEPENDENT

Refining the initial design by introducing

relationships

Relationships and Relationship Types (1)

Relationship type vs. relationship set (1)

Relationship type vs. relationship set (2)

Refining the COMPANY databaseschema by introducing relationships

Discussion on Relationship Types

Recursive Relationship Type

Weak Entity Types

Constraints on Relationships

Recursive Relationship Type is: SUPERVISION

(participation role names are shown)

Attributes of Relationship types

Notation for Constraints onRelationships

Alternative (min, max) notation forrelationship structural constraints:

Alternative diagrammatic notation

Summary of notation for ER diagrams

Extended Entity-Relationship (EER)Model (in next chapter)

Chapter Summary