원하시는 결과도 표로 보여주세요.

-- 1. Minus --
SELECT e_date, emp_no FROM a
 MINUS
SELECT e_date, emp_no FROM b
;
-- 2. Not In --
SELECT e_date
     , emp_no
  FROM a
 WHERE (e_date, emp_no) NOT IN (SELECT e_date, emp_no FROM b)
;
-- 3. Not Exists --
SELECT e_date
     , emp_no
  FROM a
 WHERE NOT EXISTS (SELECT 1
                     FROM b
                    WHERE e_date = a.e_date
                      AND emp_no = a.emp_no
                   )
;
-- 4. Outer Join & Is Null --
SELECT a.e_date
     , a.emp_no
  FROM a
  LEFT OUTER JOIN b
    ON a.e_date = b.e_date
   AND a.emp_no = b.emp_no
 WHERE b.emp_no IS NULL
;