SELECT 
coalesce(I.ITEM_CODE, IH.ITEM_CODE) AS CODE
,coalesce(I.ITEM_NAME, IH.ITEM_NAME) AS NAME
,CASE
    WHEN IH.ITEM_CODE IS NULL THEN 'ADDED'
    WHEN I.ITEM_CODE IS NULL THEN 'DELETED'
    ELSE 'UPDATED'
END
AS COMP_RSLT
/*
,I.USER_UPDATE_DATETIME AS I_TIME
,IH.USER_UPDATE_DATETIME AS H_TIME
*/
FROM ITEM AS I
    FULL OUTER JOIN ITEM_HISTORY AS IH ON I.ITEM_CODE = IH.ITEM_CODE
WHERE 
I.USER_UPDATE_DATETIME IS NULL
OR IH.USER_UPDATE_DATETIME IS NULL
OR (
    I.USER_UPDATE_DATETIME IS NOT NULL
    AND IH.USER_UPDATE_DATETIME IS NOT NULL
    AND I.USER_UPDATE_DATETIME <> IH.USER_UPDATE_DATETIME
)
ORDER BY CODE desc