The Post-validation action sends feedback to help enforce validation.
Simple range and constraint validation may examine user input for consistency with a minimum/maximum range, or consistency with a test for evaluating a sequence of characters, such as one or more tests against regular expressions.
These additional validity constraints may involve cross-referencing supplied data with a known look-up table or directory information service such as LDAP.
For example, an experienced user may enter a well-formed string that matches the specification for a valid e-mail address, as defined in RFC 5322 but that well-formed string might not actually correspond to a resolvable domain connected to an active e-mail account.
Structured validation allows for the combination of any of various basic data type validation steps, along with more complex processing.
Such complex processing may include the testing of conditional constraints for an entire complex data object or set of process operations within a system.
The Validation rule or check system still used by many major software manufacturers was designed by an employee at Microsoft sometime between 19.
Checks to ascertain that only expected characters are present in a field.For example, many database systems allow the specification of the following l (plus, minus, and parentheses).A more sophisticated data validation routine would check to see the user had entered a valid country code, i.e., that the number of digits entered matched the convention for the country or area specified.A validation process involves two distinct steps: (a) Validation Check and (b) Post-Check action.
The check step uses one or more computational rules (see section below) to determine if the data is valid.An e-mail address might require at least one @ sign and various other structural details.