Is Null
The IS NULL command is used to test for empty values (NULL values).
The following SQL lists all customers with a NULL value in the "Address" field:
Example
SELECT CustomerName, ContactName, Address
FROM Customers
WHERE Address
IS NULL;Note
A NULL value is different from a zero value or a field that contains spaces. A field with a NULL value is one that has been left blank during record creation!
Tip
Always use IS NULL to look for NULL values.