select
    it.ITEM_CODE as CODE
    ,case 
        when it.item_name = ith.item_name 
        then 'NULL'
        else it.item_name
            
    end
    as NAME
from
    item it
left join
    item_history ith
    on
    it.item_code=ith.item_code
order by
    it.item_code desc