Custom constraint for the field's value.
Source position: db.pas line 474
|  published property TField.CustomConstraint : string | 
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.
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 | Message to display if the CustomConstraint constraint is violated. | |
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 | Constraint for the field value on the level of the underlying database. |