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Entity Modeling Basics Quiz

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Questions and Answers

What is the main purpose of an entity in a database design?

To represent an object that will have many instances in the database (correct)
To represent a user of the database system
To represent an output of the database system, such as a report
To represent a concept that is not related to the database system

What is the difference between an entity type and an entity instance?

An entity type is a collection of entities with common attributes, while an entity instance is a single occurrence of an entity. (correct)
An entity type is a user of the database system, while an entity instance is an output of the database system.
An entity type is a single occurrence of an entity, while an entity instance is a collection of entities with common attributes.
An entity type is an abstract concept, while an entity instance is a physical object in the database.

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

A strong entity has a unique identifier, while a weak entity does not.
A strong entity is independent of other entities, while a weak entity is dependent on a strong entity.
A strong entity is represented by a single-line underlined identifier, while a weak entity is represented by a double-line underlined identifier.
All of the above (correct)

What is the purpose of an identifying relationship in a database design?

To link a weak entity to a strong entity (B) Signup and view all the answers

What is the main purpose of defining relationships in a database design?

To represent the connections between entities in the database (B) Signup and view all the answers

What is the purpose of modeling relationship types as lines between entity types?

To represent the specific instances of entities involved in a relationship (C) Signup and view all the answers

When does a relationship turn into an associative entity?

When it has attributes and is a many-to-many relationship (C) Signup and view all the answers

What does the degree of a relationship represent?

The number of entity types participating in the relationship (B) Signup and view all the answers

If the minimum cardinality of a relationship is zero, what does it indicate?

The relationship is optional (D) Signup and view all the answers

Which of the following statements about attributes is true?

Attributes can describe properties of both entity types and relationship types (A) Signup and view all the answers