select
  p.PORT_CODE as '港コード',
  p.PORT_NAME as '港名',
  sum(
    case when
      i.KIND_CODE = '110'
    then
      i.AMT
    else
      0
    end
  ) '入国者数',
  sum(
    case when
      i.KIND_CODE = '120'
    then
      i.AMT
    else
      0
    end
  ) '出国者数',
  sum(
    case when
      i.KIND_CODE = '110'
    then
      i.AMT
    when
      i.KIND_CODE = '120'
    then
      -i.AMT
    else
      0
    end
  ) '差分'
from
  PORT p
left join
  IMMIGRATION i
on
  p.PORT_CODE = i.PORT_CODE
group by
  p.PORT_CODE,
  p.PORT_NAME
having
  `差分` > 0
order by
  `差分` desc,
  p.PORT_CODE desc
;