select
PORT.PORT_CODE as 港コード,
PORT_NAME as 港名,
in_amt as 入国者数,
out_amt as 出国者数,
in_amt - out_amt as 差分
from (
    select 
    PORT_CODE,
    sum(case when KIND_CODE = '110' then AMT else 0 end) as in_amt, 
    sum(case when KIND_CODE = '120' then AMT else 0 end) as out_amt
    from IMMIGRATION
    where GROUP_CODE = '120'
    group by PORT_CODE
) as t1
inner join PORT on t1.PORT_CODE = PORT.PORT_CODE
where in_amt > out_amt
group by t1.PORT_CODE
order by 差分 desc, 港コード desc
;