with inn as (
    select
        *
    from
        IMMIGRATION
    where 
        GROUP_CODE = 120
        and KIND_CODE = 110
)
select
    p.PORT_CODE as 港コード
    ,p.PORT_NAME as 港名
    ,sum(inn.AMT) as 入国者数
    ,sum(imm.AMT) as 出国者数
    ,sum(inn.AMT) - sum(imm.AMT) as 差分
from
    IMMIGRATION imm
    inner join GRP g
    on imm.GROUP_CODE = g.GROUP_CODE
    inner join PORT p
    on imm.PORT_CODE = p.PORT_CODE
    left join inn
    on inn.PORT_CODE = imm.PORT_CODE
where
    imm.GROUP_CODE = 120
    and imm.KIND_CODE = 120
group by
    imm.PORT_CODE
having
    sum(inn.AMT) - sum(imm.AMT) > 0
order by
    差分 DESC
    ,港コード DESC
;