Chapter 6. Appendix A. Introduction to Databases

What Is a Database?

You can define a database as a collection of data on one topic. It is organised in a way allowing to easily browse the information, make changes or add new items.

Look at this diagram for one of the above examples: a simple phone book.



The above picture shows a set of two contacts each of which is presented on a separate card. It appears that such a card can constitute a single row in a table:

Table 6.1. Contacts table

NameTel No.

Joan

699 23 43 12

Adam

711 19 77 21


Terms and definitions: A single data which constitutes a part of a greater collection can be called a row or more professionally a record. The collection is normally called a table. Moreover, the most natural name for the table is one describing the data it offers/stores which is Contacts. Furthermore, each row in the table consists of columns often also called fields. In the table Contacts there are two columns (fields): Name and Tel No..

For simple uses a single table can make up a database. Many people consider these two equivalent. As you will see, for real databases we usually need more than one table.

To sum up, you have already got a simple database with one table Contacts.