Normalization of Databases

Question 1

What is Database Normalization?

Answer 1

Database Normalization is a systematic approach to organizing and connecting data in a relational database and a sort of refinement process for coming up with the best possible database structures as you go through the different normal forms.

Question 2

Main benefits of Database Normalization

Answer 2

Eliminates data redundancy (repetitive data) and overall finds the most efficient and refined data structure.

Question 3

What is link entity?

Answer 3

a link entity serves as an intermediary to manage many-to-many relationships between other entities in a database schema

Question 4

How to do 1NF

Answer 4

• A cell must never contain more than one value (atomic values) (e.g. column with 2 values like skill id, skill name must be defined as 2 individual columns)
• There must be a primary key meaning every row must be unique (e.g. adding Employee ID)
• Each column name must be unique
• There must be no repeating columns, they must either be removed or put into a new table

Question 5

How to do 2NF

Answer 5

• Table(s) must already be in 1NF
• All data must depend on the Primary Key (e.g. address, name would all depend on employee id but column “skill id” and “skill name” would not since that can exist by its own, therefore you must make a new table with that data or remove it)

Question 6

How to do 3NF

Answer 6

• Table(s) must already be in 2NF
• The primary key must define all non-key columns

Question 7

Foreign key

Answer 7

Any primary key that links spreadsheets or tables becomes a foreign key.