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

/*

ITEM_CODE → CODE
比較した結果→ NAME
表示順

ITEM_CODE の降順
*/