WITH 
added AS (
    SELECT
        i.ITEM_CODE AS CODE,
        i.ITEM_NAME AS NAME,
        'ADDED' AS COMP_RSLT
    FROM
        ITEM i
    LEFT JOIN ITEM_HISTORY h
    ON i.ITEM_CODE = h.ITEM_CODE
    WHERE h.ITEM_CODE IS NULL
),
updated AS (
    SELECT
        i.ITEM_CODE AS ICODE,
        i.ITEM_NAME AS INAME,
        'UPDATED' AS COMP_RSLT
    FROM
        ITEM i
    JOIN ITEM_HISTORY h
    ON i.ITEM_CODE = h.ITEM_CODE
    WHERE i.USER_UPDATE_DATETIME != h.USER_UPDATE_DATETIME
),
deleted AS (
    SELECT
        h.ITEM_CODE AS HCODE,
        h.ITEM_NAME AS HNAME,
        'DELETED' AS COMP_RSLT
    FROM
        ITEM i
    RIGHT JOIN ITEM_HISTORY h
    ON i.ITEM_CODE = h.ITEM_CODE
    WHERE i.ITEM_CODE IS NULL
),
all_data AS (
    SELECT * FROM added
    UNION ALL
    SELECT * FROM updated
    UNION ALL
    SELECT * FROM deleted
)
SELECT * FROM all_data
ORDER BY CODE DESC;