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

TField.CustomConstraint

Custom constraint for the field's value

Declaration

Source position: db.pas line 418

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

Description

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

TField.ConstraintErrorMessage

  

Message to display if the CustomConstraint constraint is violated.

TField.ImportedConstraint

  

Constraint for the field value on the level of the underlying database
The latest version of this document can be found at lazarus-ccr.sourceforge.net.