SQL IS NULL Keyword
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:
SELECT CustomerName, ContactName, Address
Try it Yourself »
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.