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