1. ©G. Millbery 2003Data, Information, Knowledge and Processing Slide 1 Validation  Making sure that the data value entered is sensible and reasonable  Types of Validation: Field Presence Check Field Length Check Range Check Format/Picture Check Check Digit

2. ©G. Millbery 2003Data, Information, Knowledge and Processing Slide 2 Types of Validation  Field Presence Check Makes sure data has been entered into a field »Called a required field in MSAccess  Field Length Check Checks the number of characters entered (minimum and maximum)  Range Check To check that the value entered is within a pre-determined range.

3. ©G. Millbery 2003Data, Information, Knowledge and Processing Slide 3 Types of Validation (cont.)  Format/Picture Check Makes sure that the data entered follows a known pattern (e.g. Postcodes, National Insurance Numbers)  Check Digit Allows a number to be self checking – the computer applies a set of rules which determines of the numbers entered are valid. (ISBN)

4. ©G. Millbery 2003Data, Information, Knowledge and Processing Slide 4 Validation and Verification  Can only ensure that the data is reasonable  Cannot guarantee accuracy  If the source data is wrong then the data entered into the system will also be incorrect Verification makes sure the source is the same as the object Validation makes sure the data is within acceptable boundaries  Neither ensures accuracy of data