Microsoft® SQL Server™ 2008 All-In-One Desk Reference For Dummies®

III.1.1. Normalizing Your Database

Normalizing a database is dividing tables into their simplest forms and creating relationships between the tables. Instead of a single table of many columns to hold all your data, you can create multiple tables and spread the data between them in a logical manner.

Tables are connected to each other by creating relationships. Relationships between tables are primarily created between the primary key in one table and a foreign key in another table.

A primary key is a column within a table that is used to uniquely identify each row within that table. Primary keys are usually numbers, but you might see them as a combination of characters and numbers in some databases. Allowing the system to generate primary keys automatically is easiest, but developers might sometimes choose to do this within their database application.

Foreign keys are used to relate one table to another table and can be a combination of numbers and letters. A foreign key is in the related column and matches the same format (numeric, character, or a combination) of the primary key in the related table.

NOTE

Book II, Chapter 4 covers relationships between tables in-depth, including the different types of relationships, how to create relationships, and maintaining relationships.

By normalizing a database, many problems can be prevented. Consider a company that sells products to customers. Information on each customer is maintained in a database, including a name, address, phone number, ...