CJV1 - Lesson 5: Normalization

normal form

A number of special properties or constraints that a relation must possess to achieve certain desired goals, such as minimizing unwanted data redundancy.

functional dependency

A relationship between two attributes indicating that for each unique attribute A, there is only one value of attribute B.

determinant

An attribute or group of attributes on which another attribute is functionally dependent.

atomic value

An attribute's value that cannot be divided into multiple pieces of information.

Which of following is designed to address the situation in which a functional dependency remains on candidate keys within a relation?

BCNF

What is required before the normalization process can be applied to a relational database?

Each instance of an entity must have a primary key that uniquely identifies that entity.

transitive dependency

In a functional dependency, if B is functionally dependent on A, and C is functionally dependent on B, C is then said to be transitively dependent on A.

partial functional dependency

In a functional dependency, when B is functionally dependent on A, and an attribute can be removed from A and the dependency still exists, B is said to be partially dependent on A.

What should you do if the normalization process decomposes relations to the point where a determinant is separated from its dependent attributes resulting in a loss of functional dependencies?

Stop the normalization process at 3NF.

What is a common occurrence when you normalize a relational database?

The amount of storage space needed for the base tables of the database will decrease.

decomposition

The process of creating new relations from existing relations based on functional dependencies within the original relation.

denormalization

The rejoining of relations that were decomposed during normalization.

Second Normal Form (2nf)

all attributes that are not part of the primary key are completely functionally dependent on the primary key.

A relation that is in 1NF is automatically in 2NF when

all determinants are candidate keys.

Boyce-Codd Normal Form (BCNF)

all determinants are candidate keys.

First Normal Form (1nf)

data is held in a two-dimensional table with each attribute represented by an atomic value.

Third Normal Form (3nf)

no attributes that are not part of the primary key are transitively dependent on the primary key.

Normalization

the process of organizing and refining relations within a relational database.