select a.ITEM_CODE as code,a.ITEM_NAME as name,'UPDATED' as COMP_RSLT
  from ITEM a join ITEM_HISTORY b
    on a.ITEM_CODE = b.ITEM_CODE
   and a.USER_UPDATE_DATETIME != b.USER_UPDATE_DATETIME
union all
select a.ITEM_CODE as code,a.ITEM_NAME as name,'ADDED' as COMP_RSLT
  from ITEM a left join ITEM_HISTORY b
    on a.ITEM_CODE = b.ITEM_CODE
 where b.ITEM_CODE is null
union all
select a.ITEM_CODE as code,a.ITEM_NAME as name,'DELETED' as COMP_RSLT
  from ITEM a right join ITEM_HISTORY b
    on a.ITEM_CODE = b.ITEM_CODE
 where a.ITEM_CODE is null
order by 1 desc