Chapter 6

Question 1

What is normalization in databases?

Answer 1

A set of concepts that is used to eliminate data redundancy and data anomalies from a database.

Question 2

What are the normal forms?

Answer 2

1

Question 3

What is the difference between 1NF, 2NF, 3NF, BCNF, and 4NF?

Answer 3

1NF: Table format, no repeating groups, and PK identified

2NF: 1NF and no partial dependencies

3NF: 2NF and no transitive dependencies

BCNF: Every determinant is a candidate key

4NF: 3NF and no independent multivalued dependencies

Question 4

How do you transform normal forms into higher and lower forms?

Answer 4

1

Question 5

When should you need to use denormalization?

Answer 5

Normalization has tiers, 2NF is better than 1NF, and 3NF is better than 2NF. But the higher tiers require more work and operations are needed so denormalization is sometimes done when the higher tiers aren’t needed. Denormalization however, increases the chance of data redundancy.

Question 6

Explain the data-modeling checklist for ERD’s

Answer 6

• Each relation (table) should represent a single subject.
• Each row and column intersection only has one value.
• Data isn’t unnecessarily stored in more than one table.
• All nonprime attributes in a relation (table) are dependent on the primary key
• Each relation (table) has no insertion, update, or deletion anomalies, which ensures the integrity and consistency of the data.

Question 7

What is partial dependency?

Answer 7

When only PART of the primary key determines the dependency. If a primary key is (A, B) and C has a dependency on B, then that’s a partial dependency.

Question 8

What is transitive dependency?

Answer 8

A two step dependency. If X -> Y and Y -> Z while X is the primary key, then it is a transitive dependency.