Advance database system(part 6)
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Advance Database Systems Enhanced Entity Relationship Diagrams (EERD)
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Transcript of 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