Data that does not conform to these rules will negatively affect business process execution.Therefore, data validation should start with business process definition and set of business rules within this process.During systems design, therefore, data definitions are established which place limits on what constitutes valid data.Using these data definitions, a range of software validation checks can be carried out.For example a numeric field may only allow the digits 0–9, the decimal point and perhaps a minus sign or commas.A text field such as a personal name might disallow characters such a markup-based security attack.
Checks to ascertain that only expected characters are present in a field.
This can only be achieved through the use of all the clerical and computer controls built into the system at the design stage.
The difference between data validity and accuracy can be illustrated with a trivial example.
Rules can be collected through the requirements capture exercise.
In evaluating the basics of data validation, generalizations can be made regarding the different types of validation, according to the scope, complexity, and purpose of the various validation operations to be carried out.