SELECT ITEM_CODE AS CODE, ITEM_NAME AS NAME, COMP_RSLT 
FROM (
SELECT I.ITEM_CODE, I.ITEM_NAME, 'ADDED' AS COMP_RSLT FROM ITEM I
WHERE
NOT EXISTS(
    SELECT
      *
    FROM
      ITEM_HISTORY IH
    WHERE
      I.ITEM_CODE = IH.ITEM_CODE
  )
UNION ALL
SELECT IH.ITEM_CODE, IH.ITEM_NAME, 'DELETED' AS COMP_RSLT FROM ITEM_HISTORY IH
WHERE
NOT EXISTS(
    SELECT
      *
    FROM
      ITEM I
    WHERE
      IH.ITEM_CODE = I.ITEM_CODE
  )
UNION ALL
SELECT I.ITEM_CODE, I.ITEM_NAME, 'UPDATED' AS COMP_RSLT FROM ITEM I
INNER JOIN ITEM_HISTORY IH
ON I.ITEM_CODE = IH.ITEM_CODE
AND I.UPDATE_USER_NAME = IH.UPDATE_USER_NAME
WHERE I.USER_UPDATE_DATETIME <> IH.USER_UPDATE_DATETIME
)
ORDER BY CODE DESC