SQL NULL Values

 

What is a NULL Value?

A field with a NULL value is a field with no value. If a field in a table is optional, it is possible to insert a new record or update a record without adding a value to this field. Then, the field will be saved with a NULL value.

The IS NULL Operator

SELECT CustomerName, ContactName, Address
FROM Customers
WHERE Address IS NULL;

The IS NOT NULL Operator

SELECT CustomerName, ContactName, Address
FROM Customers
WHERE Address IS NOT NULL;