SELECT DISTINCT
    SUB.ITEM_CODE AS CODE,
    SUB.ITEM_NAME AS NAME,
    CASE WHEN A.ITEM_CODE IS NULL THEN 'DELETED' WHEN B.ITEM_CODE IS NULL THEN 'ADDED' ELSE 'UPDATED' END AS COMP_RSLT
FROM 
    (   SELECT ITEM_CODE, ITEM_NAME, USER_UPDATE_DATETIME 
        FROM (SELECT ITEM_CODE, ITEM_NAME, USER_UPDATE_DATETIME FROM ITEM EXCEPT SELECT ITEM_CODE, ITEM_NAME, USER_UPDATE_DATETIME FROM ITEM_HISTORY)
    UNION 
    SELECT ITEM_CODE, ITEM_NAME, USER_UPDATE_DATETIME 
        FROM (SELECT ITEM_CODE, ITEM_NAME, USER_UPDATE_DATETIME FROM ITEM_HISTORY EXCEPT SELECT ITEM_CODE, ITEM_NAME, USER_UPDATE_DATETIME FROM ITEM)
    ) AS SUB
LEFT JOIN ITEM A
ON A.ITEM_CODE = SUB.ITEM_CODE
LEFT JOIN ITEM_HISTORY B
ON B.ITEM_CODE = SUB.ITEM_CODE
ORDER BY SUB.ITEM_CODE DESC