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First Normal Form

Objectives

First Normal Form

This article covers the following objectives:

  • Define the rule of First Normal Form in the normalization in database process
  • Determine if an entity conforms to the rule of First Normal Form
  • Convert an entity to First Normal Form, if needed

Purpose

  • When one of your friends changes his/her phone number. What would happen?
  • Well, it’s definitely a lot of work.
  • You have to change it in your cell phone, and from everywhere else.
  • It would take time and effort. Well, same thing can happen when dealing with the data in a database.
  • What if your friend’s phone number changes and is saved in one place and not the other—how do you know which phone number is correct?
  • Redundancy like this causes unnecessary problems in a database.
  • Normalization is a process that is used to eliminate these kinds of problems, and here we’re discussing the 1NF.

First Normal Form (1NF)

  • 1NF requires that no multi-valued attributes exist.
  • To check for 1NF, validate that each attribute has a single value for each instance of the entity.
  • One code, one name, and one address exist for the school building, but not one classroom.
First Normal Form (1NF)
  • Since many classrooms exist in a school building, classroom is multi-valued and violates 1NF.
  • If an attribute is multivalued, create an additional entity and relate it to the original entity with a 1:M relationship.

1NF Violations

  • Examine the entities.
  • Are there any multi-valued attributes?
1NF Violations

First Normal Form Example: 1NF Solutions

  • When all the attributes in an entity are single-valued, that entity is said to be in First Normal Form.
1NF Solutions

Terminology

Key terms used in this tutorial included:

  • 1NF
  • Normalization
  • Redundancy

Summary

In this tutorial, you should have learned how to:

  • Define the rule of First Normal Form in the normalization process
  • Determine if an entity conforms to the rule of First Normal Form
  • Convert an entity to First Normal Form if needed

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