SELECT
    IN_IMMIGRATION.PORT_CODE as '港コード'
    , P.PORT_NAME as '港名'
    , IN_IMMIGRATION.AMT as '入国者数'
    , OUT_IMMIGRATION.AMT as '出国者数'
    , IN_IMMIGRATION.AMT - OUT_IMMIGRATION.AMT as '差分'
FROM
    (
    SELECT
        PORT_CODE
        , I.GROUP_CODE
        , SUM(AMT) as AMT
    FROM
        IMMIGRATION as I
    INNER JOIN
        GRP as G on G.GROUP_CODE = I.GROUP_CODE and G.GROUP_CODE = '120'
    WHERE
        KIND_CODE = '110'
    GROUP BY
        PORT_CODE
    ) as IN_IMMIGRATION
INNER JOIN
    (
    SELECT
        PORT_CODE
        , I.GROUP_CODE
        , SUM(AMT) as AMT
    FROM
        IMMIGRATION as I
    INNER JOIN
        GRP as G on G.GROUP_CODE = I.GROUP_CODE and G.GROUP_CODE = '120'
    WHERE
        KIND_CODE = '120'
    GROUP BY
        PORT_CODE
    ) as OUT_IMMIGRATION on OUT_IMMIGRATION.PORT_CODE = IN_IMMIGRATION.PORT_CODE
INNER JOIN
    PORT as P on P.PORT_CODE = IN_IMMIGRATION.PORT_CODE
WHERE
    IN_IMMIGRATION.AMT > OUT_IMMIGRATION.AMT
ORDER BY
    差分 DESC
    , IN_IMMIGRATION.PORT_CODE DESC
;