IS [NOT] NULL Operator

The IS NULL operator can be used in WHERE clause predicates to match null values occurring in a specified data column. For example, the query below retrieves all PART table records that do not have a NULL value in their COLOR data column:

SELECT *
  FROM part
  WHERE color IS NOT NULL

When used in a predicate, the NULL operator keyword must be preceded with either the IS or IS NOT keywords. Operators such as =, != or ^= can not be used with NULL.