select 
ifnull(i.ITEM_CODE, ih.ITEM_CODE) CODE,
ifnull(i.ITEM_NAME, ih.ITEM_NAME) NAME,
case
    when ih.ITEM_CODE is null then "ADDED"
    when i.USER_UPDATE_DATETIME <> ih.USER_UPDATE_DATETIME then "UPDATED"
    when i.ITEM_CODE is null then "DELETED"
end as COMP_RSLT
from ITEM i
full join ITEM_HISTORY ih on i.ITEM_CODE = ih.ITEM_CODE
where
COMP_RSLT is not null
order by CODE desc
;