In an Enhanced Entity–Relationship (EER) diagram, which diagram shape represents an entity type?
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AAttribute
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BEntity
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COptional One
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DRelationship
Answer
Correct Answer: Entity
Explanation
Introduction / Context:Recognizing the core ER/EER symbols accelerates both communication and correctness in data modeling. This question focuses on the symbol for the entity type itself.
Given Data / Assumptions:
- EER notation is a superset of classic ER symbols.
- Each symbol has a fixed, widely accepted meaning.
Concept / Approach:The rectangle shape denotes an entity type. An entity type represents a set of real-world objects or concepts with shared properties. Ovals denote attributes and diamonds denote relationships; optionality and other constraints are indicated by markers and lines, not by replacing the rectangle.
Step-by-Step Solution:
Identify the asked concept: entity type.Recall symbol mapping: rectangle → entity, oval → attribute, diamond → relationship.Select Entity as the meaning of the rectangle.Verification / Alternative check:Any standard ERD legend confirms the mapping.
Why Other Options Are Wrong:
- Attribute → oval.
- Relationship → diamond.
- Optional One → not a shape; optional participation is indicated via constraints.
Common Pitfalls:Mixing up relationship diamonds and entity rectangles when relationships are named with nouns; always check the shape, not the label alone.
Final Answer:Entity