SELECT
    CASE
        WHEN ITEM_HISTORY.item_code IS NOT NULL THEN ITEM_HISTORY.item_code
        ELSE ITEM.item_code
    END AS CODE
    , CASE
        WHEN ITEM_HISTORY.item_name IS NOT NULL THEN ITEM_HISTORY.item_name
        ELSE ITEM.item_name
    END AS NAME
    , CASE
        WHEN ITEM_HISTORY.ITEM_CODE IS NULL THEN 'ADDED'
        WHEN ITEM.ITEM_CODE IS NULL THEN 'DELETED'
        WHEN ITEM_HISTORY.USER_UPDATE_DATETIME <> ITEM.USER_UPDATE_DATETIME THEN 'UPDATED'
        ELSE 'NO CHANGE'
    END AS COMP_RSLT
FROM
    ITEM_HISTORY
    FULL OUTER JOIN ITEM
    ON ITEM_HISTORY.ITEM_CODE = ITEM.ITEM_CODE
WHERE
    COMP_RSLT <> 'NO CHANGE'
;