Quiz 1&2

Which of the following attributes is not recommended to be stored in a database?

Age

A relation is in first normal form if it has no more than one multivalued attribute.

False

A relational table cannot have more than one primary key and one foreign key.

False

A well-structured relational database (i.e. one in the 3rd NF) seeks to completely eliminate redundancy so that all relations have unique/non-overlapping attributes and users can manipulate the relation without errors or inconsistencies.

False

Both primary key and foreign key cannot contain any null value.

False

In the figure shown below, a rental unit can be both an apartment and a house but must be at least one.

False

Subtypes inherit the relationships from supertype, hence the relationships a subtype participates in are always the same as the relationships the supertype participates in.

False

Unlike columns, the rows of a relation may not be interchanged and must be stored in one sequence

False

A relation that contains no multivalued attributes and has nonkey attributes solely dependent on the primary key but contains transitive dependencies is in which normal form?

Second

A supertype/subtypes hierarchy that exhibits total specialization/completeness implies that the subtype discriminator attribute in the supertype entity should not contain any null value

True

An entity instance of a subtype represents the same entity instance of the supertype.

True

If an identifier is not assigned, the default primary key for an associative relation consists of the two primary key attributes from the other two relations.

True

In a supertype/subtype hierarchy, all supertypes and subtypes share the same primary key.

True

The total completeness constraint implies that each entity of the supertype must be a member of one of the subtypes in the relationship.

True

An entity type name should be all of the following EXCEPT:

as short as possible.

An attribute that uniquely identifies an entity and consists of a composite attribute is called a(n)

composite identifier.

All of the following are the main goals of normalization EXCEPT:

consolidate tables to increase search speed.

The subtype discriminator is a simple attribute when there is a(n):

disjoint constraint.

Customers, cars, and parts are examples of:

entities.

When a regular entity type contains a multivalued attribute, one must:

keep the existing relation and create a new relation to house the multivalued attribute.

The entity integrity rule states that:

no primary key attribute can be null.

In an E-R diagram, there are ________ business rule(s) for every relationship.

two