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