Non-equijoin

The join condition in the WHERE clause may use operators other than the equal sign (=). For example, to find all employees that are not (!=) managers, the following query can be used:

SELECT lname, fname
  FROM dept, employee
  WHERE employee.e_no != dept.mgr
    AND employee.dept = dept.dept

The query result appears below:

lname fname
Hurwood Roger
Gross Mary
Wilson Arthur
Chung Yung
Cox John
Crisp Keith
Hurwood Susan
Haley Olaf