Databases and data capture

Before setting up a database, the record structure must be decided to make best use of the memory and backing store, and to make searching and report creation easier.

For example, a car showroom wants to record details of the cars it sells. Before setting up the database, the following questions need to be answered:

  1. What information is needed?
  2. What validation could there be?

With these questions answered, informed decisions can be made about the record structure. This is how it might begin:

Field nameField typeFormat
Registration numberAlphanumericUp to 7 characters - the key field
MakeAlphanumericUp to 15 characters
ModelAlphanumericUp to 15 characters
Date first registeredDateDDMMYY
PriceCurrencyUp to 5 numbers
TaxedYes/No (Boolean)1 character Y/N

When designing a database it is important to choose the correct field type. This ensures that the data stored is usable and it makes validation easier. For example, if the price paid for goods was stored in a text field, then the database wouldn’t be able to add each individual figure to produce a total.

Key fields

A database should always contain a key field.

curriculum-key-fact
The key field is a unique identifier for each record.

The following are examples of key fields:

  • car registration number
  • National Insurance number
  • your school's examination centre number
  • your own examination candidate number

Storing data in tables

Databases store data in tables, a single database file can store many tables, queries and reports. In the example table below there are six columns (divided vertically) and four rows (divided horizontally), each column has a heading, eg Registration number.

Reg. numberMakeModelDate registeredPriceTaxed
R623 PHMFordFiesta0101986800Y
P887 LHWRover2000103977500Y
P812 WHJPeugeot4060109967000N

A database in which all the data is stored in a single table is known as a flat file database.

Car showroom database onscreen with forecourt visible through the window