1. Introduction

DEFINITION: A database is a collection of data or information which is held together in an organised or logical way.

- How many of you have ever kept details of your friends or families birthdays in a birthday book?

- How many of you have written your friend's addresses into an address book?

- How many of you have a copy of the Yellow Pages at home?

If you have answered YES to any of these questions, then you have used a 'paper-based' database.

- Birthdays were organised in logical order of 'month'

- Addresses were stored in logical order of 'surname'

- Telephone numbers were stored in logical order of 'profession' e.g. gardener, builder, plumber.

These examples were of paper-based databases. However, when we use the term 'database' we generally think of a computerised database. For the purpose of this theory section and for your exam we are going to focus on computerised databases.