Getting Started Building ColdFusion MX Applications
Database Fundamentals

Understanding database basics

Even though you do not need a thorough understanding of database management systems to create ColdFusion applications, you must understand some basic concepts and techniques about databases. The information in this chapter will get you started with ColdFusion.

What is a relational database?

A relational database is a structured collection of information that is related to a particular subject or purpose, such as an inventory database or a human resources database. You use databases to manage information. Information, such as product name, cost, and on-hand inventory, is stored in a database. Within the database, you organize the data into storage containers called tables. Tables are made up of columns and rows. Columns represent individual fields in a table. Rows represent records of data in a table. You can think of database tables as grids, as in the following example:

Each field in the table contains one piece of information. In an employee table, for example, one column contains the employee name, another contains the employee phone number, and the address, city, state, zip, and salary are all stored in their own columns. Each record represents one set of related information. For example, an employee table might store information about one employee per row. The number of rows in a table represents the total number of table records.

Understanding Relational Tables

In a database, you can organize data in multiple tables. For example, if you manage a database for the Human Resource department, you might have one table that lists all the employees information and another table that lists all the departments.

Because you have multiple departments for employees, but you would not store the information about the departments in every employee row for several reasons:

• The department information is the same for each employee in a given department, however, repeating the department information for each employee is redundant. Storing redundant data takes up more disk space.
• If the department information changes, you can update one occurrence. All references to that department are updated automatically.

Storing multiple occurrences of the same data is rarely a good thing. Good relational database design separates application entities into their own tables. Key values from one table are often stored in a related table rather than repeating the information. The key value is used to join the data between the tables to return the complete set of data required.

Copyright © 2002, Macromedia Inc. All rights reserved.

Comments