NOT NULL attribute

The NOT NULL attribute specifies that the field does not accept NULL values.

Syntax

NOT NULL

Usage

The NOT NULL attribute requires that the field contains a non-null value. It can be specified explicitly in the form field definition, or in the corresponding column definition in the database schema file. If no column is associated to the field, the NOT NULL attribute can also be used in the type definition of FORMONLY fields.

Important:

For maximum security, when the data is stored in a database, define a NOT NULL constraint on the SQL column corresponding to the field, in order to deny NULL values, when an INSERT or UPDATE statement is executed.

The NOT NULL attribute is effective only when the field name appears in the list of screen fields of an INPUT or INPUT ARRAY statement.

If a DEFAULT attribute is used for the field and the input dialog does not use the WITHOUT DEFAULTS option, the runtime system assumes that the default value satisfies the NOT NULL attribute.

Unlike the REQUIRED attribute which has no effect when the INPUT dialog uses the WITHOUT DEFAULTS option, the NOT NULL attribute is always checked when validating a dialog.

Example

EDIT f001 = customer.city, NOT NULL;