with
pop_from as(
select
    PORT_CODE
    ,GROUP_CODE
    ,sum(AMT) as from_amt
from IMMIGRATION
where KIND_CODE=110 and GROUP_CODE=120
group by PORT_CODE, GROUP_CODE
)
, pop_to as(
select
    PORT_CODE
    ,GROUP_CODE
    ,sum(AMT) as to_amt
from IMMIGRATION
where KIND_CODE=120 and GROUP_CODE=120
group by PORT_CODE, GROUP_CODE
)

select
    f.PORT_CODE as '港コード'
    , po.PORT_NAME as '港名'
    , f.from_amt as '入国者数'
    , t.to_amt as '出国者数'
    , f.from_amt - t.to_amt as '差分'
from pop_from as f
inner join pop_to as t
on f.PORT_CODE = t.PORT_CODE
inner join PORT as po
on f.PORT_CODE = po.PORT_CODE
where f.from_amt > t.to_amt
order by f.from_amt - t.to_amt desc, f.PORT_CODE desc