A feature of good database design is validation.
Validation is a series of checks that can be carried out on the data entered into the fields
It is good practise to limit fields so that the values they accept :
- Are sensible
- Are valid
- Don’t waste storage space
Presences Check
A presence check can be used to ensure that data must be entered in a field.
Makes sure that the field is not left empty
For example:
- Postcode
- DOB
Field Length Check
A field length check can be used to limit the number of characters in a field.
For example:
- Forename (e.g. maximum 12 characters)
- Surname (e.g. maximum 15 characters)
- Postcode (e.g. maximum 8 characters)
Range Check
A range check can be used to ensure that data falls between two values.
For example:
- Enter a date (1 to 31)
- Enter a rating (0 to 100)
- Enter the temperature (-50 to 50)
Restricted Choice
A restricted choice check can be used to limit the user entry to a list of acceptable values.
For example:
- Day of week (Mon, Tue, Wed, Thu, Fri, Sat, Sun)
- Driving licence (Full, Provisional, None)
- Gender (Male, Female)
- Salutation (Mr, Mrs, Miss, Ms, Master, Lord, Lady, Other)
