select
a.PORT_CODE as "港コード",
PORT.PORT_NAME as "港名",
a.AMT as "入国者数",
b.AMT as "出国者数",
a.AMT - b.AMT as "差分"

from IMMIGRATION as a
inner join IMMIGRATION b
on a.PORT_CODE=b.PORT_CODE
and a.GROUP_CODE=b.GROUP_CODE

and a.KIND_CODE='110'
and b.KIND_CODE='120'
inner join PORT
on a.PORT_CODE=PORT.PORT_CODE

where a.GROUP_CODE='120'
and a.AMT > b.AMT

order by a.AMT - b.AMT desc, a.PORT_CODE desc