
A database is a way of storing informationinformation: data with context or meaning in an organised, logical way. It's important to know when to use a database and be aware of its advantages.
Before setting up a databasedatabase: a structured collection of records or data stored in a computer system, the record structure must be decided to make best use of the memorymemory: used to store data and backing storebacking store: a computer's primary data store, ie the hard disk, 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:
With these questions answered, informed decisions can be made about the record structure. This is how it might begin:
| Field name | Field type | Format |
|---|---|---|
| Registration number | Alphanumeric | Up to 7 characters - the key fieldkey field: a unique identifier for a database record or table entry |
| Make | Alphanumeric | Up to 15 characters |
| Model | Alphanumeric | Up to 15 characters |
| Date first registered | Date | DDMMYY |
| Price | Currency | Up to 5 numbers |
| Taxed | Yes/No (Boolean) | 1 character Y/N |
| ... |
When designing a database it is important to choose the correct field type. This ensures that the datadata: information without context, eg a list of students with numbers beside their names is data, when it's made clear that those numbers represent their placing in a 100 metre race, the data becomes information 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.
A database should always contain a key field.
The key field is a unique identifier for each record.
The following are examples of key fields:
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.
| Registration number | Make | Model | Date first registered | Price | Taxed |
|---|---|---|---|---|---|
| R623 PHM | Ford | Fiesta | 010198 | 6800 | Y |
| P887 LHW | Rover | 200 | 010397 | 7500 | Y |
| P812 WHJ | Peugeot | 406 | 010996 | 7000 | N |
A database in which all the data is stored in a single table is known as a flat file database.