Validation and Verification Y 11 Databases Validation and
Validation and Verification Y 11 Databases
Validation and Verification… Once you have a set of data, you need to enter it into your database system You need to devise methods to reduce the number of errors that may occur when entering data GIGO (Garbage In Garbage Out) Two of the techniques used are Validation and Verification…
Validation • Validation is performed by the computer at the point when you enter data • You create a set of rules • Validation aims to make sure that data is sensible, reasonable, complete and within acceptable boundaries • Validation does not check that the data is correct! • For example, if you type in 07/08/07 as a date of birth when it should have been 08/07/08 – validation will not pick this up!
Range Check • A range check is commonly used when you are working with data which consists of numbers, currency or dates/times • A range check allows you to set suitable boundaries:
Type Check • Setting the correct data type for the field • setting a field as NUMBER so that only “ 11” can be entered rather than “Eleven”
Check Digit • Check digits are used to make sure a range of numbers has been entered correctly • For example, barcodes and ISBN numbers • ISBN 1 84146 201 2 • The “ 2” is the check digit • The computer will perform a complex calculation based on the numbers provided and then compare the answer to the check digit
Length Check
Lookup
Picture/Format Check
Presence Check
Common Errors
Verification
Verification Methods
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