select c.PORT_CODE as 港コード,
       c.PORT_NAME as 港名,
       sum(case when a.KIND_CODE = '110' then a.AMT else 0 end) as 入国者数,
       sum(case when a.KIND_CODE = '120' then a.AMT else 0 end) as 出国者数,
       sum(case when a.KIND_CODE = '110' then a.AMT else a.AMT * (-1) end) as 差分
from IMMIGRATION a
inner join GRP   b on a.GROUP_CODE = b.GROUP_CODE
inner join PORT  c on a.PORT_CODE  = c.PORT_CODE
where b.GROUP_CODE = '120'
group by 1,2
having 差分 > 0
order by 5 desc, 1 desc