select
  port.port_code as 港コード,
  port.port_name as 港名,
  sum(case kind_code when '110' then amt else 0 end) as 入国者数,
  sum(case kind_code when '120' then amt else 0 end) as 出国者数,
  sum(case kind_code when '110' then amt else 0 end) - sum(case kind_code when '120' then amt else 0 end) as 差分
from immigration
join port
on immigration.port_code = port.port_code
join grp
on immigration.group_code = grp.group_code
where
  grp.group_code = '120' and kind_code in ('110', '120')
group by
  port.port_code, port.port_name
having
  sum(case kind_code when '110' then amt else 0 end) - sum(case kind_code when '120' then amt else 0 end) > 0
order by
  差分 desc, 港コード desc