with out1 as(
    select
        t.PORT_CODE,
        t.GROUP_CODE,
        t.KIND_CODE,
        t.AMT,
        m.PORT_NAME
    from
        IMMIGRATION as t
    inner join
        PORT as m on t.PORT_CODE=m.PORT_CODE
    where
        t.KIND_CODE = '120'
        and
        t.GROUP_CODE = '120'
)
select
    in1.PORT_CODE as 港コード,
    out1.PORT_NAME as 港名,
    in1.AMT as 入国者数,
    out1.AMT as 出国者数,
    (in1.AMT - out1.AMT) as 差分
from
    IMMIGRATION as in1
inner join
    out1 on (
            in1.PORT_CODE = out1.PORT_CODE
            and
            in1.GROUP_CODE  = out1.GROUP_CODE 
            )
where (
    in1.KIND_CODE = '110'
    and
    in1.GROUP_CODE = '120'
    and
    差分 > 0
    )
order by
    差分 desc,
    港コード desc
;