Enhanced Data Models

Enhanced Data Models

Outline
• Motivation
• EER Model
• Enhanced Data Models

• Additional concepts included
􀀹 Specialization
􀀹 Generalization
􀀹 Inheritance
• Enhanced-ER or EER model
Enhanced-ER (EER) Model Concepts
superclass
subclass
superclass/subclass relationship
Attribute Inheritance
Specialization – process of defining a set of subclasses of an entity type (super
class )
Generalization – process of defining a generalized entity type from the given
entity types.
IS-AN-INSTANCE-OF relationship (Classification & Instantiation)
IS-A-SUBCLASS-OF relationship (Specialization & Generalization)
IS-A-PART-OF / IS-A-COMPONENT-OF relationship (Aggregation &
Association)


Enhanced Data Models (1)
• Functional Data Models (FDMs):
• Use the concept of mathematical function as their fundamental
modeling construct
• Function call with arguments
• Main modeling primitives:
• Entities
• Functional relationships
• Nested Relational Data Model:
• Removes the restriction of 1NF
• Non-1NF or N1NF relational model
• Allows composite and multivalued attributes, thus leading to complex
tuples.


Enhanced Data Models (2)
• Semantic Data Model (SDM):
• Uses the concepts of classes and subclasses into data modeling
• Abstraction class
• Aggregate class
• Structural Data Model:
• Extends the relational model with additional constraints and semantics
• Structures used:
• Relations
• Primary Relation
• Referenced Relation
• connections




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