EXISTS Predicate Versus NOT IN and Nulls - Analytics Database - Teradata Vantage

For example, if all of the previous conditions are true for the following query, use NOT EXISTS instead of NOT IN:

   SELECT dept, DeptName 
   FROM Department 
   WHERE Dept NOT IN 
    (SELECT Dept 
     FROM Course);

The NOT EXISTS version looks like this:

   SELECT dept, DeptName
   FROM Department 
   WHERE NOT EXISTS
    (SELECT Dept 
     FROM Course 
     WHERE Course.Dept=Department.Dept);

That is, either Course.Dept or Department.Dept is nullable and a row from Department with a null for Dept should be returned and a null in Course.Dept should not prevent rows from Department from being returned.