select
    port.port_code as 港コード
    , port.port_name as 港名
    , sub1.for_in_amt as 入国者数
    , sub2.for_out_amt as 出国者数
    , sub1.for_in_amt - sub2.for_out_amt as 差分
from
    port
    inner join (
        select
            port_code
            , amt as for_in_amt
        from immigration
        where
            group_code = 120
            and kind_code = 110
    ) as sub1
        on port.port_code = sub1.port_code
    inner join (
        select
            port_code
            , amt as for_out_amt
        from immigration
        where
            group_code = 120
            and kind_code = 120
    ) as sub2
        on port.port_code = sub2.port_code
where
    差分 > 0
order by
    差分 desc
    , 港コード desc
;