Specifying a null value in a QBE expression
To specify that a field in the database must contain data or must not contain a data value, use the keyword Null. To specify that the field must not contain a data value, type Null as the QBE expression. To specify that a field must contain a data value, type !Null as the QBE expression. Null is not case sensitive. Table 3-1 shows examples of QBE expressions using Null.
Table 3-1 QBE expressions using Null