Data Validation

Data Validation is used to check for the accuracy of an entry. The methods of data validation are:

A Range Check: is used to restrict data entry to a specified range of numbers. For instance a range check may restrict a date entry to dd/mm/yyyy (which is day day/month month/year year year year). A range check would check if the numbers entered are within the range of 1 to 31 for dd etc…

A List Check: is when acceptable data to be entered is stored in a list and then the data entered is compared to the list. For instance if the list included all the schools in NSW then Kogarah High would be acceptable whereas Kigarah High would not be accepted unless there was another school called Kigarah High.

A Type Check: Checks to see if the correct type of data has been entered. For instance in our earlier date example an error would occur if in days “thirty one” was entered instead of “31”. One was a text type as compared to a number.

A Check Digit: A check digit is a number that is added at the end of the data. It is calculated by a formula where the other numbers are added and then put through an algorithm to end up with the number to be used as a check digit. If the data transfer or stored is wrong then the check digit would have changed and we know that the data is corrupted.