text: Last updated on January 8th, 2024 at 09:38 pm
  Because data entry on the computer is usually automated, several types of validation checks have been put in place to ensure the validity of the data being entered. These checks do not validate the accuracy of the data but rather the accuracy of the data format. For instance, if the information being entered is the date of birth in the format day/month/year, if the user enters 12/14/2022, the computer will flag this as an error. This is because part of this check will ensure the month section is not greater than 12.
  This is not the only type of check that is applied to validate the data. There are several types of validation checks. Validation checks covered in this article are:
  - Range check;
  - Check digit;
  - Format check;
  - Length check; and
  - Presence check.
  Define data validation
  Data validation refers to a way to ensure that the data you enter confirms to some predefined format and the expected data type. For instance, if the data you entered is a name, the validation check carried out will ensure that you do not enter any numbers or special characters.
  Written differently, a validation check will ensure your data is of the expected type, length, and other predefined criteria.
  In this era, where data is processed using a computer, data goes through both a validation and verification process. Read about the stages in the verification process here. Additionally, if you are interested in the key aspects of the verification process, we covered that, too.
  Types of validation checks
  There are several different types of validation checks that use different criteria. The criteria used determine the category into which each type of validation falls.
  Verification and validation are not the same things. To explore the differences between these two terms, visit the difference between validation and verification.
  This type of check simply ensures that the data entered falls within a certain range. For instance, if the age for entry into nursery school is no sooner than 3 years six months and a child is expected to leave nursery school within two years. Given that some children born late in the year may enter school at age 4, the range check may ensure the age entered for a student falls in the range of 3 to 6 years.
  Check digit data verification is a clever way to catch errors and ensure the accuracy of data, whether it’s in a barcode or on a bank cheque. Let’s look at the check digit in a barcode and bank cheque as examples:
  Barcode: Imagine you have a barcode on a product. To make sure the barcode is read correctly every time, a check digit is added to the end. This check digit is like a secret code that includes information from the other digits in the barcode.
  When you scan the product at the store, the computer checks to see if the check digit matches what it calculates based on the rest of the barcode. If they don’t match, it signals that there might be a mistake in the barcode, and the system can double-check the information. It’s like having a backup plan to catch any sneaky errors and make sure you’re buying the right product.
  Bank Cheque: Now, think about writing a cheque to pay for something. There’s a set of numbers on the bottom, and one of them is a check digit. This digit is calculated using a formula that involves the other numbers on the cheque.
  When the bank processes the cheque, it recalculates the check digit using the provided numbers. If the recalculated check digit doesn’t match the one on the cheque, the bank knows something might be off. This triggers an investigation. So, the check digit acts like a little guardian, making sure your money moves around the right way and helps to catch any mistakes or attempts at fraud early.
  A format check is used to ensure the manner in which information is entered is recognized as the correct configuration. For instance, let’s assume that a school has its students’ admission numbers set up as a six-digit code in the format of three letters, then three numbers (ABC123). A format check would ensure the first three digits entered are letters, and the last three are numbers.
  Using a date format that requires us to enter 2 numbers (03) for the day, 2 for the month (08), and 4 for the year (2002), a length check may simply ensure no less and no more than 8 digits are entered.
  This type of check simply ensures that information has been entered into the required field. That is, the fields have not been left blank.