with tmp as(SELECT ITEM_CODE CODE,
ITEM_NAME NAME,
'ADDED' COMP_RSLT
FROM ITEM i
WHERE 
not exists(select 1 from ITEM_HISTORY ih where i.item_code=ih.item_code ))
,tmp2 as(
 SELECT ITEM_CODE CODE,
ITEM_NAME NAME,
'UPDATED' COMP_RSLT
FROM ITEM i
WHERE 
exists(select 1 from ITEM_HISTORY ih
 where i.item_code=ih.item_code and i.user_update_datetime !=ih.user_update_datetime)
)
,
tmp3 as 
( SELECT ITEM_CODE CODE,
ITEM_NAME NAME ,
'DELETED' COMP_RSLT
from ITEM_HISTORY ih
where not exists (select 1 
from item i where ih.item_code=i.item_code)
),
tmp4 as (
select * from tmp2 union select * from tmp
union select * from tmp3)
select * from tmp4 order by code desc
;