| Validation and Verification : Type Check
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A type check is a validation
check which most
databases perform automatically on all entered data. When a
database is created each field in the database is given a
type. Whenever data is entered into a field the database will
check that it is of the correct type, e.g. alphabetic or numeric. If it is not then an
error message will be displayed and the data will have to be re-entered. Here are some
example field names and appropriate types.
| Field Name |
Type |
Valid Data |
Invalid Data |
| Date of Birth | Date | 11/03/96 | 30/02/76, fred |
| Sex | Alphabetic | Male, Female, Albert | 123, WA2 |
| Shoe Size | Numeric | 12, 2.3, 12323 | 6G, house |
| Postcode | Alphanumeric | W12 6BD | |
Notice that a type check is not a very good validation check. Many of the entries in the
Valid Data column in the table pass the type check but are clearly incorrect.
GCSE ICT Companion 04 - (C) P Meakin 2004