select distinct
    a.PORT_CODE as 港コード,
    b.PORT_NAME as 港名,
    d.AMT as 入国者数,
    e.AMT as 出国者数,
    d.amt - e.amt as 差分
from IMMIGRATION a
    inner join PORT b
    on a.port_code=b.port_code
    inner join GRP c
    on a.GROUP_CODE=c.GROUP_CODE
    inner join (select port_code,amt from IMMIGRATION where kind_code=110) d
    on a.port_code=d.port_code
    inner join (select port_code,amt from IMMIGRATION where kind_code=120) e
    on a.port_code=e.port_code
where c.group_code=120 and d.amt > e.amt
order by 差分 desc, a.port_code desc
;