SELECT
ITEM.ITEM_CODE as CODE
,(CASE
   WHEN
    ITEM.ITEM_NAME is not null and ITEM_HISTORY.ITEM_NAME is null
   THEN
    ITEM.ITEM_NAME
   WHEN
    ITEM.ITEM_NAME <> ITEM_HISTORY.ITEM_NAME
   THEN
    ITEM.ITEM_NAME
   ELSE null
  END) as NAME
FROM
ITEM
LEFT JOIN
ITEM_HISTORY
ON
ITEM.ITEM_CODE = ITEM_HISTORY.ITEM_CODE
ORDER BY ITEM.ITEM_CODE DESC