select
    IM.PORT_CODE AS "港コード",
    PO.PORT_NAME AS "港名",
    SUM(CASE WHEN IM.KIND_CODE = "110" THEN IM.AMT ELSE 0 END) AS "入国者数",
    SUM(CASE WHEN IM.KIND_CODE = "120" THEN IM.AMT ELSE 0 END) AS "出国者数",
    SUM(CASE WHEN IM.KIND_CODE = "110" THEN IM.AMT ELSE - IM.AMT END) AS "差分"
from 
    IMMIGRATION AS IM
    inner join PORT PO 
        on IM.PORT_CODE = PO.PORT_CODE
where 
    IM.GROUP_CODE = "120"
group by 
    IM.PORT_CODE,
    PO.PORT_NAME
having 
    "差分" > 0
order by 
    "差分" desc,
    IM.PORT_CODE desc