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