BCIS4620 CHAPTER 6 REVIEW

BCNF can be violated only if the table contains more than one _____ key.

candidate

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

True

In the context of partial dependencies, data redundancies occur because every row entry requires duplication of data.

True

An attribute that is part of a key is known as a(n) _____ attribute.

prime

When a table contains only one candidate key, _____ are considered to be equivalent.

the 3NF and the BCNF

Data warehouse routinely uses _____ structures in its complex, multilevel, multisource data environment.

2NF

From a structural point of view, 3NF is better than _____.

2NF

A table that is in 2NF and contains no transitive dependencies is said to be in _____.

3NF

A table where all attributes are dependent on the primary key but are independent of each other, and no row contains two or more multivalued facts about an entity is said to be in _____.

4NF

Normalization is a process that is used for changing attributes to entities.

False

Normalization purity is often easy to sustain in the modern database environment.

False

Some very specialized applications may require normalization beyond the _____.

4NF

In a real-world environment, we must strike a balance between design integrity and _____.

flexibility

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

partial

If a table has multiple candidate keys and one of those candidate keys is a composite key, the table can have _____ based on this composite candidate key even when the primary key chosen is a single attribute.

partial dependencies

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 relational table must not contain a(n) _____.

repeating group

An example of denormalization is using a _____ denormalized table to hold report data. This is required when creating a tabular report in which the columns represent data that are stored in the table as rows.

temporary

Granularity refers to _____.

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

Normalization works through a series of stages called normal forms. For most purposes in business database design, _____ stages are as high as you need to go in the normalization process.

three

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

To generate a surrogate key, Microsoft Access uses a(n) _____ data type.

AutoNumber

A dependency of one nonprime attribute on another nonprime attribute is a partial dependency.

False

A table is in BCNF if every determinant in the table is a foreign key.

False

Data stored at their highest level of granularity are said to be atomic data.

False

Dependencies that are based on only a part of a composite primary key are called transitive dependencies.

False

It is possible for a table in 2NF to exhibit transitive dependency, where the primary key may rely on one or more nonprime attributes to functionally determine other nonprime attributes.

True

Normalization represents a micro view of the entities within the ERD.

True

Normalization works through a series of stages called normal forms.

True

Relational models view data as part of a table or collection of tables in which all key values must be identified.

True

Repeating groups must be eliminated by ensuring that each row defines a single entity.

True

Since a partial dependency can exist only if a table's primary key is composed of several attributes, if a table in 1NF has a single-attribute primary key, then the table is automatically in 2NF.

True

The combination of normalization and ER modeling yields a useful ERD, whose entities can be translated into appropriate table structures.

True

In a(n) _____ diagram, the arrows above the attributes indicate all desirable dependencies.

dependency

From a system functionality point of view, _____ attribute values can be calculated when they are needed to write reports or invoices.

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

The objective of normalization is to ensure that each table conforms to the concept of well-formed relations.

true

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

From a structural point of view, 2NF is better than _____.

1NF

Improving _____ leads to more flexible queries.

atomicity

Of the following normal forms, _____ is mostly of theoretical interest.

DKNF

A table is in fourth normal form if it is in third normal form and has no independent multivalued dependencies.

True

Denormalization produces a lower normal form.

True

Dependency diagrams are very helpful in getting a bird's-eye view of all the relationships among a table's attributes.

True

An atomic attribute _____.

cannot be further subdivided

_____ databases reflect the ever-growing demand for greater scope and depth in the data on which decision support systems increasingly rely.

data warehouse

A table is in 4NF if it is in 3NF, and _____.

it has no multivalued dependencies

In a _____ situation, one key determines multiple values of two other attributes and those attributes are independent of each other.

multivalued dependency

The most likely data type for a surrogate key is _____.

numeric