with tmp as (
    select 
        i.PORT_CODE as 港コード,
        p.PORT_NAME as 港名,
        sum(case when i.KIND_CODE=110 then i.AMT else 0 end) as 入国者数,
        sum(case when i.KIND_CODE=120 then i.AMT else 0 end) as 出国者数,
        sum(case when i.KIND_CODE=110 then i.AMT else 0 end) - sum(case when i.KIND_CODE=120 then i.AMT else 0 end)  as 差分
    from
        IMMIGRATION as i
    left join
        PORT as p
    on
        i.PORT_CODE = p.PORT_CODE
    
    left join
        GRP as g
    on
        i.GROUP_CODE = g.GROUP_CODE
    group by
        i.PORT_CODE
    order by
        差分 desc,
        港コード desc
)
select
    *
from
    tmp
where
    差分 > 0