SELECT * FROM
(SELECT 
  ITEM_CODE,
  ITEM_NAME,
  'ADDED' AS COMP_RSLT
FROM
  ITEM
WHERE ITEM_CODE
NOT IN (
SELECT
ITEM_CODE
FROM
ITEM_HISTORY
)
UNION
SELECT 
  ITEM_CODE,
  ITEM_NAME,
  'DELETED' AS COMP_RSLT
FROM
  ITEM_HISTORY
WHERE ITEM_CODE
NOT IN (
SELECT
ITEM_CODE
FROM
ITEM
)
UNION
 SELECT 
  t1.ITEM_CODE,
  t1.ITEM_NAME,
  'UPDATED' AS COMP_RSLT
FROM
  ITEM t1
INNER JOIN
ITEM_HISTORY t2
ON
t1.ITEM_CODE = t2.ITEM_CODE
WHERE
t1.USER_UPDATE_DATETIME != t2.USER_UPDATE_DATETIME)
ORDER BY
ITEM_CODE DESC;