Searching for Nulls and Non-Nulls Together in Teradata

To search for nulls and non-nulls in the same statement, the search condition for nulls must be separate from any other search conditions.

For example, to select the names of all employees with the job title of engineer, doctor, or null,
enter the following SELECT statement.

SELECT name, jobtitle
FROM employee
WHERE jobtitle IN ('engineer', 'doctor') OR jobtitle IS NULL ;

Including NULL in the IN list has no effect because NULL never equals NULL or any value.