Database Normalization

Database normalization organizes relational tables to reduce data redundancy and prevent update anomalies. It applies a series of normal forms that determine how attributes are grouped into tables so that each fact is stored once and dependencies are explicit.

itDatabases and data storage

Database Normalization

Database normalization is a way to design relational tables around facts and their dependencies. You separate facts that describe different things. You then connect those tables with keys.

The goal is not to create as many tables as possible. The goal is to give each fact one clear home. That structure reduces repeated data and makes changes less likely to produce contradictions.

Imagine one table that records orders, customers, and products:

order_id	customer_id	customer_name	product_id	product_name	quantity
501	C7	Amara Chen	P4	Desk Lamp	2
502	C7	Amara Chen	P9	Cable Tray	1

The customer name repeats for every order line. The product name repeats whenever someone orders that product. A spelling correction must reach every copy. Missing one copy leaves the database with conflicting versions of the same fact.

A normalized design gives each fact a home:

customers stores facts about a customer.
products stores facts about a product.
orders stores facts about an order.
order_lines records which products belong to an order and in what quantity.

The order line still contains identifiers. Those identifiers are not unwanted repetition. They are keys that connect related facts.

Database Normalization

Database Normalization

The problem normalization solves

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