First Normal Form in DBMS with Examples

Lesson Transcript
Instructor: Martin Gibbs

Martin has 20 years experience in Information Systems and Information Technology, has a PhD in Information Technology Management, and a master's degree in Information Systems Management. He is an adjunct professor of computer science and computer programming.

Database normalization begins with the first normal form (1NF) in DBMS. Learn about this initial and least complex form and examine its general rules before exploring some examples of 1NF. Updated: 01/03/2022

First Normal Form

First Normal Form (1NF) is the first step in database normalization; it's a great start to reducing redundancy in the database. Before we get started on first normal form (1NF) let's quickly recap normalization.

Normalization is a process by which tables are organized in a database; the purpose is to reduce complexity. When you normalize tables, you often have to create additional tables in order to keep like data in like tables. For example, it doesn't make sense to put an entire personnel database into a single table. It's better to split out and join those items that should be related. So the employee table would be joined to a benefits table.

There are three forms of normalization, first normal, second normal, and third normal. This lesson will cover the first and least complex of the forms, first normal (1NF).

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  • 0:04 First Normal Form
  • 0:56 General Rules
  • 2:37 Examples of 1NF
  • 3:27 Lesson Summary
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General Rules

First normal may be the basic or first level, but that doesn't mean that all of the data is dumped into one table.

Each type of related data should be set up in its own table. All of the tables will contain a primary key, a unique value for each record in the table. Additionally, each data element will be granular, which means it cannot be split into smaller chunks. One example would be an employee's name, which can be broken into first and last names.

The general rules for first normal form are:

  • All tables have a primary key
  • Fields have unique names
  • Data is not repeated across fields and
  • There's no redundant data, like a field that is a combination of other fields

A primary key is a requirement for any table in a relational database. It's a unique identifier that corresponds to each row of data. Typically, it's a numerical value. Database systems automatically assign the number (usually sequential) to new entries in the table.

Field and column names must be unique. For instance, you can't have three fields named Color in a Product table. Along those same lines, having a field called Zip code and another called Postal code isn't any better, because the data being stored is the same. And this violates the next rule of 1NF: don't repeat data.

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