select
    a.port_code 港コード
    ,p.port_name 港名
    ,sum(case when KIND_CODE = 110 then amt end) 入国者数
    ,sum(case when KIND_CODE = 120 then amt end) 出国者数
    ,sum(case when KIND_CODE = 110 then amt end) - sum(case when KIND_CODE = 120 then amt end) 差分
from (
select
    PORT_CODE
    ,KIND_CODE
    ,SUM(AMT) amt
from IMMIGRATION i
where group_code = '120'
group by 
    PORT_CODE
    ,KIND_CODE
) a
join PORT p
    on p.port_code = a.port_code
group by 
    a.port_code
    ,p.port_name
having 差分 > 0
order by 差分 desc, 港コード desc