| Validation Checks
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| Presence Check
| Checks that data has been entered into a field and that it has
not been left blank. e.g. check that a surname is always entered into each record
in a database of addresses.
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| Type Check
| Checks that an entered value is of a particular type. e.g. check
that age is numeric.
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| Length Check
| Checks than an entered value e.g. surname is no longer than a
set number of characters.
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| Range Check
| Checks that an entered value falls within a particular range. For
example the age of a person should be in the range 0 to 130 years.
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| Format Check
| Checks that an entered value has a particular format. e.g. a
new-style car registration number should consist of a letter followed by 1 to
3 numbers followed by 3 letters.
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| Table Lookup Check
| Checks that an entered value is one of a pre-defined list of
valid entries which should be allowed.
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