Database

Database

Data Modeling with ER Model has 40 Questions

Which of the following indicates the maximum number of entities that can be involved in a relationship?

Minimum cardinality
Maximum cardinality
ERD
Greater Entity Count (GEC)
An ID-dependent entity is an entity whose identifier is a composite identifier where no portion of the composite identifier is an identifier of another entity.

True
False
Which type of entity cannot exist in the database unless another type of entity also exists in the database, but does not require that the identifier of that other entity be included as part of its own identifier?

Weak entity
Strong entity
ID-dependent entity
ID- independent entity
A ternary relationship is so called because in contains two entities and one association between them.

True
False
In a one-to-many relationship, the entity that is on the one side of the relationship is called a(n) ________ entity.

parent
child
instance
subtype
All instances of an entity class have the same attributes.

True
False
Which type of entity represents an actual occurrence of an associated generalized entity?

Supertype entity
Subtype entity
Archetype entity
Instance entity
A minimum cardinality is the minimum number of entity instances that may participate in a relationship instance.

True
False
A recursive relationship is a relationship between an entity and ________ .

itself
a subtype entity
an archetype entity
an instance entity
An attribute describes the entity's characteristics.

True
False
Which of the following indicates the minimum number of entities that must be involved in a relationship?

Minimum cardinality
Maximum cardinality
ERD
Greater Entity Count (GEC)
The degree of a relationship refers to the number of entity classes in the relationship.

True
False
Which of the following refers to something that can be identified in the users' work environment, something that the users want to track?

Entity
Attribute
Identifier
Relationship
Entities use identifiers while tables use keys.

True
False
In which of the following is a single-entity instance of one type related to many entity instances of another type?

One-to-One Relationship
One-to-Many Relationship
Many-to-Many Relationship
Composite Relationship
Composite identifiers consist of two or more attributes.

True
False
Which of the following refers to an entity in which the identifier of one entity includes the identifier of another entity?

Weak entity
Strong entity
ID-dependent entity
ID-independent entity
When designing a database, first identify the entities, then determine the attributes, and finally establish the relationships.

True
False
Which type of entity is related to two or more associated entities that each contain specialized attributes that apply to some but not all of the instances of the entity?

Supertype entity
Subtype entity
Archetype entity
Instance entity
A subtype entity is a special case of another entity called a supertype entity.

True
False
An attribute that names or identifies entity instances is a(n):

entity.
attribute.
identifier.
relationship.
An entity is something that can be identified in the user's work environment; something that the users want to track.

True
False
Properties that describe the characteristics of entities are called:

entities.
attributes.
identifiers.
relationships.
Entity instances are associated by relationship classes.

True
False
In which of the following can many entity instances of one type be related to many entity instances of another type?

One-to-One Relationship
One-to-Many Relationship
Many-to-Many Relationship
Composite Relationship
1:1, 1:N and N:M relationships are also known as HAS-A relationships.

True
False
Entities of a given type are grouped into a(n):

database.
entity class.
attribute.
ERD.
In a 1:N relationship, the parent is the entity on the one side of the relationship and the child is the entity on the N side of the relationship.

True
False
Which of the following is NOT a basic element of all versions of the E-R model?

Entities
Attributes
Relationships
Primary keys
A maximum cardinality is the maximum number of entity instances that can participate in a relationship instance.

True
False
In which of the following is a single-entity instance of one type of related to a single-entity instance of another type?

One-to-One Relationship
One-to-Many Relationship
Many-to-Many Relationship
Composite Relationship
An entity class is a collection of entities and is described by the structure of the entities in that class.

True
False
Entities can be associated with one another in which of the following?

Entities
Attributes
Identifiers
Relationships
Relationship classes are associations between entity classes.

True
False
Which type of entity has its relationship to another entity determined by an attribute in that other entity called a discriminator?

Supertype entity
Subtype entity
Archetype entity
Instance entity
An identifier typically uses more than one attribute.

True
False
Which type of entity represents a logical generalization whose actual occurrence is represented by a second, associated entity?

Supertype entity
Subtype entity
Archetype entity
Instance entity
An identifier determines the type of relationship that an entity has.

True
False
In a one-to-many relationship, the entity that is on the many side of the relationship is called a(n) ________ entity.

parent
child
instance
subtype
A recursive relationship is a relationship between an archetype and an instance of that archetype.

True
False