Advance database system(part 6)

Advance Database SystemsEnhanced Entity Relationship Diagrams (EERD)

Contents

• Enhanced Entity Relationship Diagrams (EERD)

• Sub Type and Super Type Relationships

Enhanced Entity Relationship Diagrams (EERD)

Sub Type and Super Type Relationships

Basic Concept and Notation

Attribute Inheritance

When to use Supertype/Subtype Relationships

Representing Specialization and Generalization

Specialization

Specifying Constraint in Sub Type/Super Type Relationships

Total Specialization/Partial Specialization Rule

Specifying Disjointness Constraints

Disjoint Rule/Overlap Rule

Defining Subtype Discriminators

Disjoint Subtype

Defining Super Type/Sub Type Hierarchies