select
    it.item_code as CODE
    ,CASE WHEN it.item_name == ih.item_name THEN NULL
         WHEN it.item_name != ih.item_name THEN it.item_name
         WHEN ih.item_name IS NULL THEN it.item_name
    END as NAME
from
    ITEM it
    LEFT JOIN ITEM_HISTORY ih
      ON ih.ITEM_CODE = it.ITEM_CODE
order by
    it.ITEM_CODE desc