select
    I2.PORT_CODE as 港コード,
    PORT.PORT_NAME as 港名,
    I1.AMT as 入国者数,
    I2.AMT as 出国者数,
    (I1.AMT - I2.AMT) as 差分
from
    IMMIGRATION as I1
    inner join IMMIGRATION as I2
        on I1.PORT_CODE = I2.PORT_CODE
        and I1.GROUP_CODE = I2.GROUP_CODE
        and I2.KIND_CODE = '120'
    inner join GRP
        on I1.GROUP_CODE = GRP.GROUP_CODE
    inner join PORT
        on I1.PORT_CODE = PORT.PORT_CODE
where
    I1.GROUP_CODE = '120'
    and I1.KIND_CODE = '110'
    and I1.AMT - I2.AMT > 0
order by
    (I1.AMT - I2.AMT) desc,
    I2.PORT_CODE desc
;