3. Why use a database?

There are a number of reasons why a database is the most suitable application for storing information.

Vast amounts of information can be stored.

Think of high street banks. They have millions of customers who might have more than one account with them. They might have a current account, a savings account and a mortgage account. Within each of these accounts, there will be a number of transactions taking place on a regular basis. Money will be paid in and money will be withdrawn for payment of items. The banks need to be able to store details of every single transaction which takes place, what time it happened, how much money was involved, who was paid etc. Multiply this by millions of customers and you soon have a huge database with an immense amount of data being stored.

Queries can be run to search for specific records or groups of records.

Again, let's go back to our bank example.

A customer telephones the bank to complain that a withdrawal of money was made from their account which they don't recognise. The bank needs to be able to search its database very quickly and find the customer's account, the transaction and the details involved. This can all be done in a matter of seconds.

Reports can be produced from the data stored or queries run

Whilst tables hold lots of data and that data can be sorted into a logical order or extracted as part of a query, the output doesn't look very professional.

If you are just searching the database for information for yourself, that would be fine, but if you are going to show the information to a manager or a customer, it needs to be presented in a more professional way, probably with the company house style and logo as well.

This can be done by producing a database report.

Information can be extracted from the database and exported into a word processing package for mail merging

Most official (or spam) letters that you receive will be personally addressed to you. They have your name, your address, your account details and perhaps even information about things that you have previously bought.

All of this is done by running a query on a database and finding a set of records which match a set of criteria, for example, 'everyone who lives in Birmingham and who purchased something in the last month'.

The data from the query is then automatically extracted from the database and placed into a pre-written letter, merged, printed and sent to you. This technique enables companies to contact thousands of people very quickly.

Validation can be used to reduce errors

As you know from module 3.1.1, validation can't stop errors, but it can be used to reduce errors. Databases enable you to use a variety of validation techniques to ensure that data is 'reasonable, allowable, sensible and within acceptable boundaries'.