select distinct
im.port_code as 港コード
,port.port_name as 港名
,nyukoku.amt as 入国者数
,syukkoku.amt as 出国者数
,nyukoku.amt-syukkoku.amt as 差分
from immigration as im
inner join(select port_code,amt from immigration where group_code = '120' and kind_code ='110') as nyukoku
on nyukoku.port_code = im.port_code
inner join(select port_code,amt from immigration where group_code = '120' and kind_code ='120') as syukkoku
on syukkoku.port_code = im.port_code
inner join port
on port.port_code = im.port_code
where 入国者数>出国者数
order by 差分 desc,港コード desc