Understanding validation rules
Validation rules are criteria that a DataWindow object uses to validate
data entered into a column by users. They are PowerBuilder-specific
and therefore not enforced by the DBMS.
Validation rules assigned in the Database painter are used by default
when you place columns in a DataWindow object. You can override the default
rules in the DataWindow painter.
A validation rule is an expression that evaluates to either “true” or “false”.
If the expression evaluates to “true” for an entry
into a column, PowerBuilder accepts the entry. If the expression evaluates
to “false”, the entry is not accepted and the
ItemError event is triggered. By default, PowerBuilder displays a
message box to the user. You can customize the message displayed when
a value is rejected.
You can also code the ItemError event to cause different processing
to happen.
For more information, see the chapter on using DataWindow objects
in the DataWindow Programmers Guide.
At runtime
In scripts, you can use the GetValidate method
to obtain the validation rule for a column and the SetValidate method
to change the validation rule for a column.
For information about the GetValidate and SetValidate methods,
see the online help.