select
    p.PORT_CODE as 港コード,
    p.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
    PORT p
inner join
    IMMIGRATION i1
on
    p.PORT_CODE = i1.PORT_CODE and
    i1.KIND_CODE = 110 and
    i1.GROUP_CODE = 120
inner join
    IMMIGRATION i2
on
    p.PORT_CODE = i2.PORT_CODE and
    i2.KIND_CODE = 120 and
    i1.AMT > i2.AMT
order by
    i1.AMT - i2.AMT desc,
    p.PORT_CODE desc
;