select 
    IM1.PORT_CODE as "港コード",
    PORT.PORT_NAME as "港名",
    IM1.AMT as "入国者数",
    IM2.AMT as "出国者数",
    (IM1.AMT - IM2.AMT) as "差分"
from
    IMMIGRATION as IM1
    inner join IMMIGRATION as IM2
        on IM1.PORT_CODE = IM2.PORT_CODE
        and IM1.GROUP_CODE = IM2.GROUP_CODE
        and IM2.KIND_CODE = "120"
        and IM2.GROUP_CODE = "120"
    inner join PORT ON PORT.PORT_CODE = IM1.PORT_CODE
    inner join GRP ON GRP.GROUP_CODE = IM1.GROUP_CODE
where
    IM1.KIND_CODE = "110"
    and IM1.GROUP_CODE = "120"
    and "差分" > 0
order by
    "差分" desc,
    IM1.PORT_CODE desc