Progress
Language Tutorial
for Windows


Validation Expressions and Messages

Validation is the process of checking criteria before allowing the user to take an action. There are two types of validation: table validation and field validation. Table validation allows you to establish criteria that must be met before a user can delete a record. For example, you wouldn’t want to delete a customer record if that customer has unpaid bills.

To see an example of table validation, access the property sheet for the Customer table and choose the Validation button. The dialog box shown in Figure 4–8 appears.

Figure 4–8: Table Validation Dialog Box

Field validation allows you to establish what is and is not an acceptable entry for a field. For example, you can check to make sure an entry falls with high and low numeric limits.

To see an example of field validation, access the property sheet for the Credit-Limit field of the Customer table and choose the Validation button. The dialog box shown in Figure 4–9 appears.

Figure 4–9: Field Validation Dialog Box

Both of these dialog boxes have an editor widget where you can define the validation criteria using Progress 4GL statements. This code is known as the validation expression.

The fill-in widget contains text that Progress displays to the user when a user action fails the validation expression. This message is known as the validation message.


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