select 
i.ITEM_CODE as CODE
,case when h.ITEM_CODE is null then i.ITEM_NAME
    when i.ITEM_NAME <> h.ITEM_NAME then i.ITEM_NAME
    else null end as NAME
from ITEM i
left join ITEM_HISTORY h
on i.ITEM_CODE = h.ITEM_CODE
order by i.ITEM_CODE desc