About validation rules
When users enter data in a DataWindow object, you want to be
sure the data is valid before using it to update the database. One
way to do this is through validation rules.
You usually define validation rules in the Database painter.
To use a validation rule, you associate it with a column in the
Database painter or DataWindow Object painter.
Another technique You can also perform data validation through code tables,
which are implemented through a column’s edit style.
For more information, see “About edit styles “.
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 Object 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 DataWindow Programmer’s 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.