An ER Model includes I. An ER diagram portraying entity types. II. Attributes…
2013
An ER Model includes
I. An ER diagram portraying entity types.
II. Attributes for each entity type
III. Relationships among entity types.
IV. Semantic integrity constraints that reflects the business rules about data not captured in the ER diagram.
- A.
I, II, III & IV
- B.
I & IV
- C.
I, II & IV
- D.
I & III
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Correct answer: A
Answer: All four statements are part of the ER model.
Explanation:
Entity types: The ER diagram identifies the main entities (for example, Customer, Order, Product).
Attributes: Each entity type has attributes that describe its properties (for example, Customer has Name, Address).
Relationships: The model shows relationships among entity types (for example, Customer places Order), which are essential to represent connections.
Semantic integrity constraints: These are business rules (for example, "an order must have at least one order line") that may not be fully captured by the diagram notation but are part of the ER model specification.
Why other combinations are incomplete: Omitting attributes or relationships leaves out necessary structural detail, and omitting semantic integrity constraints ignores business rules that govern valid data. Therefore a complete ER model includes all four elements.