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