select 
p.PORT_CODE as "港コード",
p.PORT_NAME as "港名",
--i.KIND_CODE,
--i.AMT,
case when i.KIND_CODE = 110 then i.AMT else 0 end as "入国者数",
case when i.KIND_CODE = 120 then i.AMT else 0 end as "出国者数",
"入国者数" - "出国者数" as "差分"
from IMMIGRATION i
left outer join GRP g
on i.GROUP_CODE = g.GROUP_CODE
left outer join PORT p
on i.PORT_CODE = p.PORT_CODE
order by "差分" asc, "港コード" desc
;