select
    p.PORT_CODE as 港コード,
    p.PORT_NAME as 港名,
    sum(ifnull(case when im.KIND_CODE = "110" then AMT end, 0)) as 入国者数,
    sum(ifnull(case when im.KIND_CODE = "120" then AMT end, 0)) as 出国者数,
    sum(ifnull(case when im.KIND_CODE = "110" then AMT end, 0)) - sum(ifnull(case when im.KIND_CODE = "120" then AMT end, 0)) as 差分
from
    PORT as p
inner join
    IMMIGRATION as im
    on p.PORT_CODE = im.PORT_CODE
where
    im.GROUP_CODE = "120"
group by
    1, 2
having
    差分 > 0
order by
    5 desc, 1 desc