SELECT
    CASE WHEN I_CODE IS NULL THEN IH_CODE
        ELSE I_CODE END AS CODE
    ,NAME
    ,CASE WHEN I_CODE IS NULL THEN 'DELETED'
       WHEN IH_CODE IS NULL THEN 'ADDED'
       ELSE 'UPDTED' END AS COMP_RSLT
FROM
(SELECT I.ITEM_CODE AS I_CODE
    ,IH.ITEM_CODE AS IH_CODE
    ,I.ITEM_NAME AS NAME
    ,CASE WHEN I.USER_UPDATE_DATETIME = IH.USER_UPDATE_DATETIME THEN 'NOT UPDATE'
          ELSE 'UPDATED' END AS COMP_RSLT
    ,'1'
FROM ITEM I
LEFT OUTER JOIN ITEM_HISTORY IH ON I.ITEM_CODE = IH.ITEM_CODE
UNION ALL
SELECT I2.ITEM_CODE AS I_CODE
    ,IH2.ITEM_CODE AS IH_CODE
    ,IH2.ITEM_NAME AS NAME
    ,'' AS COMP_RSLT
    ,'2'
FROM ITEM_HISTORY IH2
LEFT OUTER JOIN ITEM I2 ON IH2.ITEM_CODE = I2.ITEM_CODE
) AA
WHERE AA.I_CODE IS NULL
   OR AA.IH_CODE IS NULL
   OR AA.COMP_RSLT = 'UPDATED'
ORDER BY CASE WHEN I_CODE IS NULL THEN IH_CODE
        ELSE I_CODE END DESC
;