with l_item as (
select distinct ITEM_CODE,
ITEM_NAME,
USER_UPDATE_DATETIME
from ITEM
),
o_item as (
select distinct ITEM_CODE,
ITEM_NAME,
USER_UPDATE_DATETIME
from ITEM_HISTORY
)
select ITEM_CODE CODE,
ITEM_NAME NAME,
'ADDED' COMP_RSLT
from l_item
where ITEM_CODE not in(select ITEM_CODE from o_item)
union all
select ITEM_CODE CODE,
ITEM_NAME NAME,
'DELETED' COMP_RSLT
from o_item
where ITEM_CODE not in(select ITEM_CODE from l_item)
union all
select ITEM_CODE CODE, l_item.ITEM_NAME NAME, 'UPDATED' COMP_RSLT
from l_item
inner join o_item using(ITEM_CODE)
where l_item.USER_UPDATE_DATETIME != o_item.USER_UPDATE_DATETIME
order by 1 desc