select a.ITEM_CODE as CODE,
 case when a.ITEM_NAME a.ITEM_NAME = b.ITEM_NAME then null
 when a.ITEM_NAME a.ITEM_NAME <> b.ITEM_NAME then a.ITEM_NAME a.ITEM_NAME
 end NAME
 from ITEM as a
 left join ITEM_HISTORY as b
 on  a.ITEM_CODE = b.ITEM_CODE