with w as (
    select
        i.PORT_CODE as PORT_CODE,
        p.PORT_NAME as PORT_NAME,
        sum(case when KIND_CODE = '110' then AMT else 0 end) as AMT_IN,
        sum(case when KIND_CODE = '120' then AMT else 0 end) as AMT_OUT
    from
        IMMIGRATION as i
    join
        PORT as p 
        on i.PORT_CODE = p.PORT_CODE
    where
        i.GROUP_CODE = '120'
    group by 
        p.PORT_CODE, p.PORT_NAME
)

select
 PORT_CODE as 港コード,
 PORT_NAME as 港名,
 AMT_IN    as 入国者数,
 AMT_OUT   as 出国者数,
 AMT_IN - AMT_OUT as 差分
from 
    w
where 
 AMT_IN > AMT_OUT
order by 
 差分 desc,
 港コード desc
;