SELECT e.last_name, m.manager_id FROM employees e RIGHT OUTER JOIN employees m on (e.manager_id = m.employee_id) AND e.employee_id = 123;
SELECT e.last_name, m.manager_id FROM employees e LEFT OUTER JOIN employees m on (e.employee_id = m.manager_id) WHERE e.employee_id = 123;
SELECT e.last_name, e.manager_id FROM employees e RIGHT OUTER JOIN employees m on (e.employee_id = m.employee_id) WHERE e.employee_id = 123;
SELECT m.last_name, e.manager_id FROM employees e LEFT OUTER JOIN employees m on (e.manager_id = m.manager_id) WHERE e.employee_id = 123;