If you create a statement that returns records where a specific column's records contain a null value, and your statement is returning no records, check that you are using the correct syntax.
In the following example, the statement will retrieve no records because = NULL is used:
SELECT Invoices.CustomerID, Invoices.OrderID FROM Invoices WHERE ( Invoices.Region = NULL )
To retrieve records, use IS NULL, as shown in the following example:
SELECT Invoices.CustomerID, Invoices.OrderID FROM Invoices WHERE ( Invoices.Region IS NULL )
