select
img_in.port_code as "港コード",
port.port_name as "港名",
img_in.amt as "入国者数",
img_out.amt as "出国者数",
img_in.amt - img_out.amt as "差分"
from
(select * from immigration where kind_code = '110') img_in
inner join (select * from immigration where kind_code = '120') img_out
on img_in.port_code = img_out.port_code
inner join port
on img_in.port_code = port.port_code
where
img_in.amt > img_out.amt
order by
"差分" desc,
"港コード" desc