select
    wk1.PORT_CODE as "港コード",
    wk2.PORT_NAME as "港名",
    sum(case when KIND_CODE = "110" then wk1.AMT else 0 end) as "入国者数",
    sum(case when KIND_CODE = "120" then wk1.AMT else 0 end) as "出国者数",
    sum(case when KIND_CODE = "110" then wk1.AMT else 0 end) - sum(case when KIND_CODE = "120" then wk1.AMT else 0 end) as "差分"
from
    IMMIGRATION as wk1
inner join
    PORT as wk2
on
    wk1.PORT_CODE = wk2.PORT_CODE
where
    wk1.GROUP_CODE = "120"
group by
    wk1.PORT_CODE
having
    差分 > 0
order by
    差分 desc,
    港コード desc
;