with tmp1 as (
    /*追加されたデータ*/
    select 
        t1.item_code as CODE,
        t1.item_name as NAME,
        'ADDED' as COMP_RSLT
    from item as t1
    left outer join item_history as t2
    on t1.item_code=t2.item_code
    where t2.item_code is null
),
tmp2 as (
    /*削除されたデータ*/
    select 
        t1.item_code as CODE,
        t1.item_name as NAME,
        'DELETED' as COMP_RSLT
    from item_history as t1
    left outer join item as t2
    on t1.item_code=t2.item_code
    where t2.item_code is null
),
tmp3 as (
    /*更新されたデータ*/
    select 
        t1.item_code as CODE,
        t1.item_name as NAME,
        'UPDATED' as COMP_RSLT
    from item as t1
    inner join item_history as t2
    on t1.item_code=t2.item_code
    where t1.user_update_datetime>t2.user_update_datetime
)
select * from tmp1
union all select * from tmp2
union all select * from tmp3
order by code desc;