select
t1.PORT_CODE as "港コード",
p.PORT_NAME as "港名",
sum(t1.AMT) as "入国者数",
sum(t2.AMT) as "出国者数",
sum(t1.AMT) - sum(t2.AMT) as "差分"
from IMMIGRATION as t1
inner join PORT as p
on t1.PORT_CODE = p.PORT_CODE
inner join IMMIGRATION as t2
on t1.PORT_CODE = t2.PORT_CODE
and t2.KIND_CODE = "120"
and t1.AMT >= t2.AMT
where t1.KIND_CODE = "110"

group by
t1.PORT_CODE
order by
差分 desc,t1.PORT_CODE desc