select 
    pt.port_code             as 港コード
,   pt.port_name             as 港名
,   vw.inbound               as 入国者数
,   vw.outbound              as 出国者数
,   vw.inbound - vw.outbound as 差分
from
(
    select
        im.port_code
    ,   sum(case when im.kind_code = '110' then im.amt else 0 end) as inbound
    ,   sum(case when im.kind_code = '120' then im.amt else 0 end) as outbound
    from
        IMMIGRATION im
    inner join
        grp gp
    on
        gp.group_code = im.group_code
    where
        gp.group_name = '外国人'
    group by
        im.port_code
    having 
        sum(case when im.kind_code = '110' then im.amt else 0 end) -- inbound
        > sum(case when im.kind_code = '120' then im.amt else 0 end) --outbound
)   vw
inner join
    port pt
on
    pt.port_code = vw.port_code
order by
    vw.inbound - vw.outbound desc
,   pt.port_code desc