Info 3233 Quizzes

At the implementation level, the supertype and its subtype(s) depicted in a specialization hierarchy maintain a(n) _____ relationship.

1:1

A table that has all key attributes defined, has no repeating groups, and all its attributes are dependent on the primary key is said to be in _____.

1NF

When a nonkey attribute is the determinant of a key attribute, the table is in 3NF but not in _____.

BCNF

_____ expresses the minimum and maximum number of entity occurrences associated with one occurrence of the related entity.

Cardinality

PRODUCT yields all possible pairs of rows from two tables, also known as the _____ product.

Cartesian

_____ are important because they help to ensure data integrity.

Constraints

A weak relationship exists if the primary key of the related entity contains at least one primary key component of the parent entity.

False

Entity subtypes do not inherit the relationships in which the supertype entity participates.

False

In a natural join, the column on which the join was made occurs twice in the new table.

False

The SELECT operator yields a vertical subset of a table.

False

The external model is the representation of the database as "seen" by the DBMS.

False

The one-to-many (1:M) relationship is easily implemented in the relational model by putting the foreign key of the "1" side in the table of the "many" side as a primary key.

False

The entity relationship model uses the associative entity to represent a(n) _____ relationship between two or more entities.

M:N

A(n) _____ relationship is also known as an identifying relationship.

Strong

Which of the following is a specialization hierarchy disjoint constraint scenario in case of partial completeness?

Subtype discriminator can be null.

Which of the following is a specialization hierarchy overlapping constraint scenario in case of partial completeness?

Supertype has optional subtypes.

Which of the following is true of business rules?

They can serve as a communication tool between the users and designers.

A composite identifier is a primary key composed of more than one attribute.

True

A weak entity has a primary key that is partially or totally derived from the parent entity in the relationship.

True

Each row in the relational table is known as an entity instance or entity occurrence in the ER model.

True

If the attribute (B) is functionally dependent on a composite key (A) but not on any subset of that composite key, the attribute (B) is fully functionally dependent on (A).

True

In order to meet performance requirements, portions of the database design may need to be occasionally denormalized.

True

In the context of data models, an entity is a person, place, thing, or event about which data will be collected and stored.

True

M:N relationships are not appropriate in a relational model.

True

The DIFFERENCE operator subtracts one table from the other.

True

The DIVIDE operation uses one single-column table (e.g., column "a") as the divisor and one two-column table (e.g., columns "a" and "b") as the dividend.

True

A partial completeness constraint is represented by _____.

a single horizontal line under a circle

A _____ key can be described as a minimal superkey, a superkey without any unnecessary attributes.

candidate

An atomic attribute _____.

cannot be further subdivided

A(n) _____ is a restriction placed on the data.

constraint

The decision to store _____ attributes in database tables depends on the processing requirements and the constraints placed on a particular application.

derived

Attribute A _____ attribute B if all of the rows in the table that agree in value for attribute A also agree in value for attribute B.

determines

A relationship is an association between _____.

entities

A(n) _____ only returns matched records from the tables that are being joined.

inner join

When designing a database, you should _____.

make sure that entities are in normal form before table structures are created

A(n) _____ join links tables by selecting only the rows with common values in their common attribute(s).

natural

The "_____" characteristic of a primary key states that the primary key should not have embedded semantic meaning.

non intelligent

Within a specialization hierarchy, every subtype can have _____ supertype(s) to which it is directly related.

only one

Dependencies based on only a part of a composite primary key are known as _____ dependencies.

partial

_____ completeness means that not every supertype occurrence is a member of a subtype.

partial

A _____ derives its name from the fact that a collection of multiple entries of the same type can exist for any single key attribute occurrence.

repeating group

A(n) _____ is the conceptual organization of an entire database as viewed by a database administrator.

schema

An internal _____ refers to a specific representation of an internal model, using the database constructs supported by the chosen database.

schema

A(n) _____ is the attribute in the supertype entity that determines to which entity subtype each supertype occurrence is related.

subtype discriminator

A _____ is a primary key created by a database designer to simplify the identification of entity instances.

surrogate key

Granularity refers to _____.

the level of detail represented by the values in a table's row

A(n) _____ exists when there are functional dependencies such that Y is functionally dependent on X, Z is functionally dependent on Y, and X is the primary key.

transitive dependency

Each row in a relation is called a(n) _____.

tuple

A _____ relationship exists when an association is maintained within a single entity.

unary

A _____ entity has a primary key that is partially or totally derived from the parent entity in the relationship.

weak