select
t1.port_code as 港コード,
pt.port_name as 港名,
t1.amt as 入国者数,
t2.amt as 出国者数,
t1.amt - t2.amt as 差分
from immigration as t1
inner join immigration as t2
on t1.port_code = t2.port_code
and t1.group_code =t2.group_code
and t2.group_code = '120'
inner join port as pt
on t1.port_code = pt.port_code
where t1.kind_code = '110'
and t1.group_code = '120'
and 差分>0
order by  差分 desc,t1.port_code desc;