[Overview][Constants][Types][Classes][Procedures and functions][Variables][Index] Reference for unit 'DB' (#fcl)


Custom constraint for the field's value


Source position: db.pas line 443

published property TField.CustomConstraint : string
  read FCustomConstraint
  write FCustomConstraint;


CustomConstraint may contain a constraint that will be enforced when the dataset posts it's data. It should be a SQL-like expression that results in a True or False value. Examples of valid constraints are:

Salary < 10000
YearsEducation < Age

If the constraint is not satisfied when the record is posted, then an exception will be raised with the value of ConstraintErrorMessage as a message.

This feature is not yet implemented in FPC.

See also



Message to display if the CustomConstraint constraint is violated.



Constraint for the field value on the level of the underlying database

Documentation generated on: May 14 2021