WITH TMP(CODE) AS (
    SELECT
        ITEM_CODE
    FROM ITEM
    
    UNION
    
    SELECT 
        ITEM_CODE
    FROM ITEM_HISTORY
)

SELECT
    T.CODE AS CODE,
    CASE
        WHEN H.ITEM_CODE IS NULL THEN I.ITEM_NAME
        WHEN I.ITEM_CODE IS NULL THEN H.ITEM_NAME
        ELSE H.ITEM_NAME
    END AS NAME,
    CASE 
        WHEN H.USER_UPDATE_DATETIME IS NULL THEN 'ADDED'
        WHEN I.USER_UPDATE_DATETIME IS NULL THEN 'DELETED'
        WHEN H.USER_UPDATE_DATETIME<>I.USER_UPDATE_DATETIME THEN 'UPDATED'
        ELSE NULL
    END AS COMP_RSLT
FROM TMP AS T
LEFT OUTER JOIN (
        SELECT 
            ITEM_CODE,
            ITEM_NAME,
            USER_UPDATE_DATETIME
        FROM ITEM
        WHERE USER_UPDATE_DATETIME>='2023-12-31 00:00:00'
        ) AS I
    ON T.CODE=I.ITEM_CODE
LEFT OUTER JOIN ITEM_HISTORY AS H
    ON T.CODE=H.ITEM_CODE
WHERE COMP_RSLT IS NOT NULL
ORDER BY CODE DESC;