with cte as (select
    a.ITEM_CODE as CODE
    ,a.ITEM_NAME as an
    ,b.ITEM_NAME as bn
from
    ITEM as a
    left join
    ITEM_HISTORY as b
    on a.ITEM_CODE = b.ITEM_CODE
)
select 
    CODE
    ,case 
        when bn is null then an
        when an=bn then null
        else an
    end as NAME
from 
    cte
order by CODE desc