Databases and data capture
A database is a way of storing information [information: 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 database [database: a structured collection of records or data stored in a computer system ], the record structure must be decided to make best use of the memory [memory: used to store data ] and backing store [backing 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 field [key 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 data [data: 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|
A database in which all the data is stored in a single table is known as a flat file database.
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