select
    PORT_CODE as 港コード,
    PORT_NAME as 港名,
    sum(
        case
            KIND_CODE
            when 110 then AMT
            else 0
        end
    ) as 入国者数,
    sum(
        case
            KIND_CODE
            when 120 then AMT
            else 0
        end
    ) as 出国者数,
    sum(
        case
            KIND_CODE
            when 110 then AMT
            when 120 then - AMT
            else 0
        end
    ) as 差分
from
    IMMIGRATION
    inner join GRP using(GROUP_CODE)
    inner join PORT using(PORT_CODE)
where
    GROUP_CODE = 120
group by
    PORT_CODE
having
    差分 > 0
order by
    差分 desc,
    PORT_CODE desc;