select
    p.PORT_CODE as '港コード',
    p.PORT_NAME as '港名',
    kind110.AMT as '入国者数',
    kind120.AMT as '出国者数',
    kind110.AMT - kind120.AMT as '差分'
from
   PORT as p
   left outer join (select * from IMMIGRATION where GROUP_CODE = 120 and KIND_CODE = 110) as kind110 on kind110.PORT_CODE = p.PORT_CODE
   left outer join (select * from IMMIGRATION where GROUP_CODE = 120 and KIND_CODE = 120) as kind120 on kind120.PORT_CODE = p.PORT_CODE
where
    kind110.AMT > kind120.AMT
order by
    差分 desc,
    港コード desc
;