select
ifnull(ITEM.ITEM_CODE, ITEM_HISTORY.ITEM_CODE) as CODE
,ifnull(ITEM.ITEM_NAME, ITEM_HISTORY.ITEM_NAME) as NAME
,case
    when ITEM_HISTORY.USER_UPDATE_DATETIME IS NULL then 'ADDED'
    when ITEM.USER_UPDATE_DATETIME IS NULL then 'DELETED'
    when ITEM.USER_UPDATE_DATETIME <> ITEM_HISTORY.USER_UPDATE_DATETIME then 'UPDATED'
    end as COMP_RSLT
from ITEM
full outer join ITEM_HISTORY
on ITEM.ITEM_CODE = ITEM_HISTORY.ITEM_CODE
where
    ITEM.USER_UPDATE_DATETIME <> ITEM_HISTORY.USER_UPDATE_DATETIME
    or ITEM.USER_UPDATE_DATETIME IS NULL
    or ITEM_HISTORY.USER_UPDATE_DATETIME IS NULL
order by CODE desc
;