ER Model

Given the basic ER and relational models, which of the following is INCORRECT?

• An attribute of an entity can have more than one value

• An attribute of an entity can be composite

• In a row of a relational table, an attribute can have more than one value

• In a row of a relational table, an attribute can have exactly one value or a NULL value

Consider the following ER diagram. The minimum number of tables needed to represent M, N, P, R1, R2 is:

• 2

• 3

• 4

• 5

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

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

• Supertype entity

• Subtype entity

• Archetype entity

• Instance entity

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

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

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

• entity

• attribute.

• identifier.

• relationship.

Properties that describe the characteristics of entities are called:

• entities.

• attributes.

• identifiers.

• relationships.

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

• Entities

• Attributes

• Relationships

• Primary keys

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

• Entities

• Attributes

• Identifiers

• Relationships