What happens if data is stored in more than one place in a database? What if someone changes the information in one place and not the other—how do you know which information is correct?

CMIS 320 Project 4

Objectives
• This lesson covers the following objectives:
−Define the purpose of normalization in database models
−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

Purpose
• Think about storing your friends’ phone numbers in three different places:
−your address book, your cell phone, and a sheet of paper that you have taped to your refrigerator
• It’s a lot of work if a friend changes his/her phone number
• You have to change it in your address book, cell phone, and the sheet of paper taped to your refrigerator

Purpose
• What happens if data is stored in more than one place in a database?
• What if someone changes the information in one place and not the other—how do you know which information is correct?
• Redundancy like this causes unnecessary problems in a database

Purpose
• Normalization is a process that is used to eliminate these kinds of problems
• One of your goals as a database designer is to “store information in one place and in the best possible place“
• If you follow the rules of normalization, you will achieve this goal