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