Normalization

Normalization is the process of organizing data in a database to reduce redundancy and improve data integrity.

Redundancy

Redundant data refers to duplicate data that is stored in multiple places within a database. For instance, if you have two tables:

  1. Users
  2. Orders

and the following structure:

Users Table

UserID Name Username
1 Alice Smith asmith
2 Bob Johnson bjohnson

Orders Table (with redundancy)

OrderID UserID Name Product Quantity
101 1 Alice Smith Laptop 1
102 2 Bob Johnson Smartphone 2

In this example, the Orders table includes the user's name, even though the same information is already present in the Users table. This is redundant data.

Despite the redundancy, this schema can still function correctly. Given a user ID, we can retrieve all orders associated with that user. Similarly, we can find the user's details (username, name) using an order ID.

Non-Full Proof Data

Users Table

UserID Name Username
1 Alice Smith asmith
2 Bob Johnson bjohnson