select
    PORT.PORT_CODE as '港コード',
    PORT_NAME as '港名',
    nyuukoku_gaigokujin.AMT as '入国者数',
    syukkoku_gaigokujin.AMT as '出国者数',
    nyuukoku_gaigokujin.AMT - syukkoku_gaigokujin.AMT as '差分'
from
    PORT
    inner join (
        select
            PORT_CODE,
            AMT
        from
            IMMIGRATION
        where
            GROUP_CODE = '120'
            and KIND_CODE = '110'
    ) as nyuukoku_gaigokujin on PORT.PORT_CODE = nyuukoku_gaigokujin.PORT_CODE
    inner join(
        select
            PORT_CODE,
            AMT
        from
            IMMIGRATION
        where
            GROUP_CODE = '120'
            and KIND_CODE = '120'
    ) as syukkoku_gaigokujin on PORT.PORT_CODE = syukkoku_gaigokujin.PORT_CODE
where
    nyuukoku_gaigokujin.AMT > syukkoku_gaigokujin.AMT
order by 
    nyuukoku_gaigokujin.AMT - syukkoku_gaigokujin.AMT desc,
    PORT.PORT_CODE desc