WITH added AS (
    SELECT
        I.ITEM_CODE,
        I.ITEM_NAME,
        H.USER_UPDATE_DATETIME
    FROM
        ITEM AS I
            LEFT OUTER JOIN ITEM_HISTORY AS H 
                ON I.ITEM_CODE = H.ITEM_CODE 
    WHERE
        H.USER_UPDATE_DATETIME IS NULL OR
        I.USER_UPDATE_DATETIME >  H.USER_UPDATE_DATETIME
),

deleted AS (
    SELECT
        H.ITEM_CODE,
        H.ITEM_NAME,
        I.USER_UPDATE_DATETIME
    FROM
        ITEM_HISTORY AS H
            LEFT OUTER JOIN ITEM AS I 
                ON H.ITEM_CODE = I.ITEM_CODE 
    WHERE
        I.USER_UPDATE_DATETIME IS NULL
)

SELECT 
    ITEM_CODE AS CODE,
    ITEM_NAME AS NAME,
    CASE 
        WHEN USER_UPDATE_DATETIME IS NULL THEN 'ADDED'
        ELSE 'UPDATED'
    END AS COMP_RSLT
FROM
    added
UNION
SELECT 
    ITEM_CODE AS CODE,
    ITEM_NAME AS NAME,
    'DELETED' AS COMP_RSLT
FROM
    deleted
ORDER BY
    CODE DESC;