EER Model Concepts and Relationships

What is the primary purpose of the Enhanced Entity-Relationship (EER) model?

• To replace the traditional E-R model

• To extend the E-R model with additional modeling constructs

• To simplify database design by removing relationships

• To enforce strict one-to-one relationships in all cases

Which of the following best describes a supertype in the EER model?

• A generic entity type with common attributes shared by its subtypes

• A subgrouping of entities with distinct attributes

• A relationship between two entities

• A constraint that ensures uniqueness in a database

In the context of supertype/subtype relationships, attribute inheritance means:

• In the context of supertype/subtype relationships, attribute inheritance means:

• Subtypes inherit all attributes and relationships from the supertype

• Only unique attributes are inherited by the subtypes

• Each subtype must have completely different attributes from the supertype

What symbol represents a Total Specialization constraint in an EER diagram?

• A single line

• A dashed line

• A double line

• A diamond shape

If an instance of a supertype must be a member of at least one subtype, which rule applies?

• Partial Specialization Rule

• Total Specialization Rule

• Disjoint Rule

• Overlap Rule

Overlap Rule

• Combining multiple entities into one supertype

• Dividing an entity into multiple subtypes

• Ensuring that an entity belongs to a subtype

• • Eliminating redundancy in a database

A supertype/subtype hierarchy is used when:

• All attributes are unique to individual entities

• An entity has multiple categories with shared and unique attributes

• Every entity is independent and has no common attributes

• Every entity is independent and has no common attributes

The disjoint rule ensures that:

• An instance of a supertype can belong to multiple subtypes

• An instance of a supertype can only belong to one subtype

• A supertype must always have multiple subtypes

• The supertype can exist without any subtypes

A subtype discriminator is:

• A unique identifier for each subtype

• An attribute that determines which subtype an entity belongs to

• A relationship between subtypes

• A rule that forces specialization

Overlapping subtypes occur when:

• An instance of a supertype can belong to multiple subtypes

• An instance of a supertype must belong to only one subtype

• A supertype has no attributes

• Subtypes are unrelated to each other