karim-aboelazm / database_normalization

Normalization is the process of organizing data in a database efficiently. It involves structuring a database in a way that reduces redundancy and dependency of data. The primary goals of normalization are to minimize redundancy, avoid anomalies during data modification, and ensure data integrity.

Here are examples of different normalization forms:

First Normal Form (1NF):

In 1NF, each column in a table contains atomic (indivisible) values, and each column has a unique name.

Example: Consider a table StudentCourses:

StudentID	Name	Courses
1	John	Math, Physics
2	Sarah	Chemistry, Biology
3	Alex	Math, Chemistry, Gym

To convert this to 1NF, separate the repeating groups into individual rows:

StudentID	Name	Course
1	John	Math
1	John	Physics
2	Sarah	Chemistry
2	Sarah	Biology
3	Alex	Math
3	Alex	Chemistry
3	Alex	Gym

Second Normal Form (2NF):

In 2NF, the table is in 1NF, and all non-key attributes are fully dependent on the primary key.

Example: Consider a table Sales:

OrderID	Product	Category	Price
1	Laptop	Electronics	1000
2	TV	Electronics	800
3	Banana	Fruits	10

In this case, Category is partially dependent on the primary key. To achieve 2NF, create separate tables:

Products:

ProductID	Product	CategoryID
1	Laptop	1
2	TV	1
3	Banana	2

Categories:

CategoryID	Category
1	Electronics
2	Fruits

Third Normal Form (3NF):

In 3NF, the table is in 2NF, and there is no transitive dependency (non-key attributes depending on other non-key attributes).

Example: Consider a table Employees:

EmployeeID	EmployeeName	Department	DepartmentLocation
1	John	IT	Building A
2	Sarah	HR	Building B
3	Alex	IT	Building A

Here, DepartmentLocation depends on Department, not directly on the primary key EmployeeID. To achieve 3NF:

Employees:

EmployeeID	EmployeeName	DepartmentID
1	John	1
2	Sarah	2
3	Alex	1

Departments:

DepartmentID	Department	Location
1	IT	Building A
2	HR	Building B

This breaks the transitive dependency, isolating DepartmentLocation into the Departments table.