SELECT
  CASE
    WHEN ih.ITEM_CODE IS NULL THEN i.ITEM_CODE
    WHEN i.ITEM_CODE IS NULL THEN ih.ITEM_CODE
    ELSE i.ITEM_CODE
  END AS CODE
, CASE
    WHEN ih.ITEM_CODE IS NULL THEN i.ITEM_NAME
    ELSE ih.ITEM_NAME
  END AS NAME
, CASE
    WHEN ih.ITEM_CODE IS NULL THEN 'ADDED'
    WHEN i.ITEM_CODE IS NULL THEN 'DELETED'
    WHEN i.USER_UPDATE_DATETIME != ih.USER_UPDATE_DATETIME THEN 'UPDATED'
  END AS COMP_RSLT
FROM
  ITEM i
  FULL OUTER JOIN ITEM_HISTORY ih ON i.ITEM_CODE = ih.ITEM_CODE
WHERE
  i.ITEM_CODE IS NULL
  OR ih.ITEM_CODE IS NULL
  OR i.USER_UPDATE_DATETIME != ih.USER_UPDATE_DATETIME
ORDER BY
  CODE DESC;