Database normalisation facts for kids

Database normalization is a clever way to design computer databases. Imagine you have lots of information, like details about students and the classes they take. Instead of putting everything into one giant list, database normalization helps you sort this information into smaller, organized groups called tables. These tables are then linked together, making it easier to find and manage data.

Think of it like organizing your school supplies. You wouldn't throw all your pens, pencils, and erasers into one big box. Instead, you might put pens in one holder, pencils in another, and erasers in a small pouch. This makes it much easier to find what you need quickly!

What is a Database?

A database is like a super-organized digital filing cabinet. It stores information so computers can find it quickly. There are different kinds of databases.

Relational Databases

The most common type is a relational database. This is where information is stored in separate tables, just like our example with students and classes. Each table focuses on one type of information. For example, one table might hold all student names and IDs, and another table might list all the classes offered. These tables are connected by special links, so the database knows which student is in which class.

Flat File Databases

Before relational databases, many people used "flat file databases." Imagine a giant spreadsheet where all information is crammed into one big list. If a student takes three classes, their name and address might be repeated three times. This can lead to several problems:

• Lots of empty space: If a student only takes one class, there might be many blank spots for other classes.
• Repeated information: Repeating data takes up more space and makes the database bigger than it needs to be.
• More mistakes: If you need to change a student's address, you have to change it in many places. If you miss one, you'll have different addresses for the same student, causing errors.

Why Do We Need Normalization?

Database normalization helps us design relational databases in the best way possible. It's like having a set of rules to make sure your organized school supplies stay perfectly tidy.

The main goals of normalization are:

• Reduce mistakes: By storing each piece of information only once, it's much harder for errors to creep in. If a student's address changes, you only update it in one spot.
• Save space: No more repeating information! This makes the database smaller and faster.
• Keep data accurate: It ensures that the information in your database is always correct and consistent.

Normal Forms: The Rules for Good Design

A computer scientist named Edgar F. Codd came up with the idea of database normalization in the 1970s. He created a set of rules called "normal forms." If a database table follows these rules, it's considered "normalized."

There are several normal forms, each with its own set of rules. The more rules a database follows, the more organized and less prone to errors it becomes. Codd first described three main normal forms:

• First normal form
• Second normal form
• Third normal form

Later, more normal forms were added:

• Fourth normal form
• Fifth normal form

Following these rules helps protect the database from problems that can happen when information is added, changed, or deleted. The only small downside is that sometimes, getting certain information out of a very normalized database can be a tiny bit more complicated, but the benefits usually outweigh this.