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 (WITHOUT DEFAULTS is not used), and a
DEFAULT attribute is defined
for the field, or the program variable corresponding to the field is initialized with a non-NULL
value in BEFORE INPUT, BEFORE INSERT or BEFORE
DIALOG, 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;