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nf3_tutorial - The 3 Normal Forms A Tutorial by Fred...

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The 3 Normal Forms: A Tutorial by Fred Coulson Copyright © Fred Coulson 2007 (last revised February 1, 2009) This tutorial may be freely copied and distributed, providing appropriate attribution to the author is given. Inquiries may be directed to http://phlonx.com/contact Downloaded from http://phlonx.com/resources/nf3/

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Table of Contents 3 Normal Forms Tutorial http://phlonx.com/resources/nf3/ 1 Table of Contents TABLE OF CONTENTS . ...................................................................................... 1 INTRODUCTION . ................................................................................................. 2 THE PROBLEM: KEEPING TRACK OF A STACK OF INVOICES . ................................................ 3 FIRST NORMAL FORM: NO REPEATING ELEMENTS OR GROUPS OF ELEMENTS. ............................ 5 SECOND NORMAL FORM: NO PARTIAL DEPENDENCIES ON A CONCATENATED KEY. ......................... 8 SECOND NORMAL FORM: PHASE II . ........................................................................................................... 12 THIRD NORMAL FORM: NO DEPENDENCIES ON NON-KEY ATTRIBUTES. ......................................... 15 REFERENCES FOR FURTHER READING . ...................................................... 18
Introduction 3 Normal Forms Tutorial http://phlonx.com/resources/nf3/ 2 Introduction This is meant to be a very brief tutorial aimed at beginners who want to get a conceptual grasp on the database normalization process. I find it very difficult to visualize these concepts using words alone, so I shall rely as much as possible upon pictures and diagrams. To demonstrate the main principles involved, we will take the classic example of an Invoice and level it to the Third Normal Form. We will also construct an Entity Relationship Diagram (ERD) of the database as we go. Important Note: This is not a description of how you would actually design and implement a database. The sample database screenshots are not meant to be taken literally, but merely as visual aids to show how the raw data gets shuffled about as the table structure becomes increasingly normalized. Purists and academics may not be interested in this treatment. I will not cover issues such as the benefits and drawbacks of normalization. For those who wish to pursue the matter in greater depth, a list of references for further reading is provided at the end. For the most part, the first three normal forms are common sense. When people sit down to design a database, they often already have a partially-normalized structure in mind—normalization is a natural way of perceiving relationships between data and no special skill in mathematics or set theory is required. In fact, it usually takes quite a bit of work to

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nf3_tutorial - The 3 Normal Forms A Tutorial by Fred...

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