SET NULL Command Example

The following example demonstrates how SET NULL affects support for null values. The first table, employee, is created with SET NULL ON, so its fields support null values. REPLACE is used to place a null value in the cLastName field. The second table, staff, is created with SET NULL OFF, so its fields do not support null values. REPLACE is used to place zero in the cLastName field.

CLOSE DATABASES
SET NULL ON        && Fields will support null values
CREATE TABLE employee (cLastName C(20), ySalary Y(12,2))
APPEND BLANK       && Add a new blank record
REPLACE cLastName WITH .NULL.  && cLastName supports null values

SET NULL OFF       && Fields will not support null values
CREATE TABLE staff (cLastName C(20), ySalary Y(12,2))
APPEND BLANK       && Add a new blank record
REPLACE cLastName WITH 0   && Doesn't support null values