select
    COALESCE(IH.ITEM_CODE, I.ITEM_CODE) AS CODE,
    COALESCE(IH.ITEM_NAME, I.ITEM_NAME) AS NAME,
    case
        when ih.item_code is null then 'ADDED'
        when i.item_code is null then 'DELETED'
        when i.USER_UPDATE_DATETIME <> ih.USER_UPDATE_DATETIME then 'UPDATED'
        else ''
    end as COMP_RSLT
from
    item as i
left join
    item_history as ih
on
    i.item_code = ih.item_code
where
    COMP_RSLT <> ''
union
select
    COALESCE(IH.ITEM_CODE, I.ITEM_CODE) AS CODE,
    COALESCE(IH.ITEM_NAME, I.ITEM_NAME) AS NAME,
    case
        when ih.item_code is null then 'ADDED'
        when i.item_code is null then 'DELETED'
        when i.USER_UPDATE_DATETIME <> ih.USER_UPDATE_DATETIME then 'UPDATED'
        else ''
    end as COMP_RSLT
from
    item as i
right join
    item_history as ih
on
    i.item_code = ih.item_code
where
    COMP_RSLT <> ''
order by
    code desc