Databases

Databases enable people to store and retrieve information using a computer.

A database works like a card filing system, eg for people's addresses. Each card might look like this:

  ----------------------------
 | Employee number: 27
 |
 | First name: John
 | Last name: Smith
 | Home phone: 01274 333444
 | Mobile: 07799 888999
 | Address: 3 High Street
 | City: Bradford
 | Postcode: BD1 1LT
  ----------------------------

Each card is a record which refers to a single object/person/thing in the database and in the real world. This card refers to a person: John Smith.

Each line on the card is a field which refers a piece of information about the person (their last name, mobile number, etc).

Once information has been entered into the fields in the computer's 'cards' (records) it can be retrieved in various ways to answer questions which would be difficult to answer using a card system:

eg Find all customers who live in Bradford but don't have a telephone

Different types of database

How the data gets into the database and how you ask questions is different for different databases.

For simple use (cataloging recipes, CD collections, club memberships, etc), Microsoft Works or Filemaker Pro are a good choice. Databases are easy to create and query. There are half a dozen types of field to choose from (general, numbers, text, dates, times, etc) and your information is stored as a table like a spreadsheet, with field names across the top and a line for each record

In real life, things aren't simple. A hundred people work for a single company. The company has multiple offices. Projects may be worked on by different people from different offices! When you need to store information about different, but related items, you need a 'relationtional' database management system (RDBMS) such as Microsoft Access or Open Office.

An RDBMS ties together information in stored in different tables by matching on a unique ID. Mr Smith's personal information, address, employment details & projects could all be stored in four separate tables, tied together by his unique employee ID:

  ----------------------------
 | Employee ID: 27
  ----------------------------
 | First name: John
 | Last name: Smith
 | Address ID: 33
 | Company ID: 27

  ----------------------------
 | Address ID: 33
  ----------------------------
 | Address: 3 High Street
 | City: Bradford
 | Postcode: BD1 1LT

  ----------------------------
 | Company ID: 27
  ----------------------------
 | Name: Super Plastics
 | Projects: 1027, 133, 96

  ----------------------------
 | Project ID: 1027
  ----------------------------
 | Companies involved: 27, 36, 87
 | Team members: 27, 95, 13

The Big Picture

As you tie together more information, your database becomes more powerful. This can lead to privacy concerns, for instance when information in a cable TV companies database is tied together with an income profile database to generate customised advertising aimed at specific households.

Information is held in databases regarding which cash points you've used, which shops you've spent money in, the locations you've made mobile phone calls from. Google ties together all the searches you've made from your computer. Yahoo and MSN create customised adverts based on your geographic location determined from your computer's IP address.

Databases are everywhere. They can be used for our benefit, or to profit the unscrupulous. You may one day end up collecting information for databases or using databases to extract information. Your boss may ask you to 'bump up the figures' to make the department look good and ensure the budget doesn't get cut. What if you work in a bank and a friend asks you to look up their boyfriend's credit rating?

Information itself is neutral - neither good nor bad. What matters is how it's used. To reflect the truth with integrity, honesty & openness? Or to distort reality, put information into the wrong hands and knowingly damage reputations?

Web Links

• Database Theory

Category: ICT

Author: Mr Kershaw