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