select 
i.port_code as '港コード'
,p.port_name as '港名'
,i.amt as '入国者数'
,out.amt as '出国者数'
,i.amt-out.amt as '差分'
from immigration as i
inner join port as p
on i.port_code=p.port_code
inner join immigration as out
on i.port_code=out.port_code
and i.group_code=out.group_code
and out.kind_Code='120'
and i.kind_code='110'
where i.amt-out.amt>0
and i.group_code='120'
order by i.amt-out.amt desc,i.port_code desc