with org as (
select
    port_code
    , case when kind_code=110 then amt else 0 end as _1
    , case when kind_code=120 then amt else 0 end as _2
from IMMIGRATION
where (group_code = 120 and kind_code = 110)
    or (group_code = 120 and kind_code = 120)
), org2 as (
select
    a.port_code as '港コード'
    , b.port_name as '港名'
    , sum(a._1) '入国者数'
    , sum(a._2) '出国者数'
    , sum(a._1) - sum(a._2) as '差分'
from org as a
inner join port as b
    on a.port_code = b.port_code
group by a.port_code
order by 5 desc, 1 desc
)
select * from org2
where 差分 > 0
;