Checking Inputs

• Validation is a system which automatically checks if data satisfies a specified criteria (it checks if data is reasonable). Types are range check, presence check, type check, length check, and check digit.
• Check digit are calculated from numerical data, e.g. a barcode, and added onto the end of the data.
• Verification is a system which checks the integrity of data when it is entered into a system. An example is checking the input data against the original document or record.
• Double entry in which data is entered twice and the entries are compared to identify differences.
• Accuracy of data entry is an important consideration in system design. Inaccurate data can lead to inaccurate outputs.
• Validation is a technique in which the system checks data input against a set of predetermined rules. It can identify obvious errors by detecting data that fails to meet the validation rules. It is able to ensure that data input is reasonable but cannot guarantee data accuracy.
• Validation:

  • Presence checks ensure that the data has been input.
  • Range checks ensure that data falls within a predetermined range of values.
  • Length checks ensure that data inputs contain a predetermined number of characters.
  • Type checks ensure that data input is of a certain type.
  • Format checks ensure that data input meets a predetermined format.
  • Check digits are calculated from numerical data such as a barcode and added to the end of the data.
• It is possible to check that specific characters are present in a string. This can be used to either accept only if the required characters are used or to reject if unacceptable characters are included.
• Verification checks the integrity of data when it is entered into a the system. This is often completed by the individual inputting the data.
• Verification:

  • Checking the input data against the original document or record.
  • Double entry in which the data is entered twice and the entries compared to identify differences.