Entity-Relationship Modeling: A Comprehensive Guide for Database Design

Question 1

In the ER model, what is the cardinality of a one-to-one relationship?

Accepted Answer

Exactly one entity can relate to exactly one other entity.

Answer

One entity can relate to many other entities, but not vice versa.

Answer

Many entities can relate to one other entity, but not vice versa.

Answer

Many entities can relate to many other entities.

Question 2

Which notation is widely used to represent Entity-Relationship (ER) diagrams?

Accepted Answer

Crow's Foot notation

Answer

Unified Modeling Language (UML)

Answer

Business Process Model and Notation (BPMN)

Answer

Entity-Relationship Diagram (ERD)

Question 3

Which constraint type specifies that an attribute must always have a non-null value?

Accepted Answer

Mandatory

Answer

Optional

Answer

Unique

Answer

Foreign key

Question 4

Identify the type of relationship where one entity can be associated with numerous instances of another entity.

Accepted Answer

One-to-many

Answer

One-to-one

Answer

Many-to-one

Answer

Many-to-many

Question 5

Describe the main distinction between an entity and an attribute.

Accepted Answer

Entities represent real-world objects, while attributes describe their characteristics.

Answer

Attributes represent real-world objects, while entities describe their characteristics.

Answer

Entities and attributes are essentially the same concept.

Answer

Both entities and attributes are used to depict relationships.

Question 6

Explain the purpose of normalizing an ER diagram.

Accepted Answer

Reduce data duplication and enhance data integrity

Answer

Increase the complexity of the ER diagram

Answer

Make the ER diagram more visually appealing

Answer

Create a physical database schema

Question 7

In Crow's Foot notation, which symbol represents a strong entity in an ER diagram?

Accepted Answer

Double line rectangle

Answer

Single line rectangle

Answer

Single line ellipse

Answer

Double line ellipse

Question 8

In an Entity-Relationship Model, what distinguishes a strong entity from a weak entity?

Accepted Answer

Strong entities can exist independently, while weak entities require a strong entity to exist.

Answer

Strong entities rely on weak entities for existence, while weak entities can exist independently.

Answer

Weak entities have their own unique identifier, while strong entities do not.

Question 9

How does Entity-Relationship (ER) modeling aid in the design of relational databases?

Accepted Answer

It identifies entities and relationships, creating a logical data model.

Answer

It directly generates SQL commands for database creation.

Answer

It automates data normalization.

Question 10

In an Entity-Relationship model, which attribute types are simple, composite, multivalued, and derived?

Accepted Answer

Simple, Composite, Multivalued, Derived

Answer

Simple, Composite, Single-valued, Derived

Answer

Atomic, Compound, Repeating, Calculated

Question 11

In Entity-Relationship Modeling, which of the following is NOT a fundamental component of an entity?

Accepted Answer

Operation

Answer

Identifier

Answer

Attribute

Answer

Relationship

Question 12

What is the primary purpose of a cardinality constraint in an ER diagram?

Accepted Answer

To specify the minimum and maximum number of related instances between entities.

Answer

To define the specific type of relationship between entities.

Answer

To identify the primary key of an entity.

Answer

To ensure data integrity by preventing incompatible relationships.

Question 13

When representing a many-to-many relationship in an ER diagram, which approach is commonly used?

Accepted Answer

Associative entity

Answer

Weak entity

Answer

Bridging table

Answer

Recursive relationship

Question 14

What is the primary role of an attribute in an ER diagram?

Accepted Answer

Describing the characteristics or properties of entities or relationships.

Answer

Identifying the primary key of an entity.

Answer

Specifying cardinality constraints.

Answer

Representing the data stored in the database.

Question 15

What is the primary goal of normalization in ER modeling?

Accepted Answer

Reducing data redundancy and enhancing data integrity.

Answer

Creating a more efficient database design.

Answer

Simplifying the ER diagram.

Answer

Increasing database flexibility.

Question 16

Develop an ER diagram for a university system that includes students, courses, and enrollments. Explain how the diagram is structured to capture the relationships between these entities.

Accepted Answer

ER diagram with STUDENT, COURSE, and ENROLLMENT entities, relationships with correct cardinality and attributes.

Answer

ER diagram with STUDENT and COURSE entities only, no ENROLLMENT entity.

Answer

ER diagram with STUDENT and COURSE entities, but incorrect cardinality in the relationship.

Answer

ER diagram with only one entity, STUDENT, and no relationships.

Question 17

In Entity-Relationship Modeling, which component represents a real-world object or concept?

Accepted Answer

Entity

Answer

Connector

Answer

Attribute

Answer

Relationship

Question 18

Which of the following is NOT an advantage of using ER modeling?

Accepted Answer

Complex data structures cannot be represented.

Answer

Improved communication among stakeholders

Answer

Enhanced data integrity

Question 19

Which attribute type serves as a unique identifier for entities?

Accepted Answer

Primary key

Answer

Foreign key

Answer

Composite key

Answer

Secondary key

Question 20

In ER modeling, which concept represents a logical connection between entities?

Accepted Answer

Relationship

Answer

Connector

Answer

Entity

Answer

Attribute

Question 21

What is the primary purpose of weak entities in ER modeling?

Accepted Answer

Representing entities dependent on other entities for their existence

Answer

Representing relationships among entities

Answer

Identifying attributes unrelated to an entity

Question 22

Which component of an Entity-Relationship Diagram (ERD) represents a real-world object, concept, or event?

Accepted Answer

Entity

Answer

Attribute

Answer

Relationship

Answer

Connector

Question 23

What is the primary purpose of an attribute in an ERD?

Accepted Answer

To describe a characteristic or property of an entity

Answer

To represent a relationship between entities

Answer

To define constraints on an entity or relationship

Answer

To connect entities to each other

Question 24

What is the key difference between a weak and a strong entity?

Accepted Answer

Weak entities cannot exist independently of a strong entity.

Answer

Strong entities cannot have multiple instances related to a weak entity.

Answer

Weak entities have fewer attributes than strong entities.

Answer

Weak entities are always involved in hierarchical relationships.

Question 25

Which of the following is a potential limitation of ER modeling?

Accepted Answer

Creating complex ERDs can be time-consuming.

Answer

ER modeling is not suitable for large-scale databases.

Answer

ER modeling does not support object-oriented concepts.

Question 26

What is the main purpose of an entity identifier?

Accepted Answer

To uniquely identify each instance of an entity within the ERD

Answer

To describe the properties or characteristics of the entity

Answer

To enforce business rules related to the entity

Answer

To connect entities to relationships in the ERD

Question 27

How does a composite attribute differ from a simple attribute in an ERD?

Accepted Answer

A composite attribute is made up of multiple simple attributes combined together.

Answer

Simple attributes cannot be used in relationships, while composite attributes can.

Answer

Composite attributes are only used in weak entities, while simple attributes are used in strong entities.