REQUIRED attribute
The REQUIRED attribute forces the user to modify the content of a field during
an input dialog.
Syntax
REQUIREDUsage
The REQUIRED attribute forces the user to modify the content of a field
controlled by an input dialog (INPUT or INPUT ARRAY), when the
INPUT dialog does not use the WITHOUT DEFAULTS option.
Within INPUT ARRAY, the REQUIRED attribute always applies to newly
created rows.
If an INPUT dialog uses the WITHOUT DEFAULTS
clause, the current value of the variable linked to the REQUIRED field
is considered as a default value; the runtime system assumes that the field satisfies the
REQUIRED attribute, even if the variable value is null.
In an INPUT ARRAY dialog, the REQUIRED attribute always applies
to newly created rows, even if WITHOUT DEFAULTS is used. In other words, when
creating a new row, INPUT ARRAY behaves like INPUT
without the WITHOUT DEFAULTS clause.
If REQUIRED is effective regarding the WITHOUT
DEFAULTS conditions, and a DEFAULT attribute is used for
the field, the runtime system assigns the default value to the field and assumes that
the REQUIRED attribute is satisfied.
The REQUIRED attribute does not prevent fields being null; If the field contains
a value, and the user subsequently erases this value during the same input, the runtime system
considers the REQUIRED attribute satisfied. To insist on a non-null entry, use the
NOT NULL attribute.
Example
EDIT f001 = orders.ord_shipcmt, REQUIRED;