SELECT
    IM1.PORT_CODE AS "港コード",
    PT.PORT_NAME AS "港名",
    IM1.AMT AS "入国者数",
    IM2.AMT AS "出国者数",
    (IM1.AMT - IM2.AMT) AS "差分"
FROM
    IMMIGRATION AS IM1
    INNER JOIN IMMIGRATION AS IM2
        ON IM2.PORT_CODE = IM1.PORT_CODE
        AND IM2.GROUP_CODE = IM1.GROUP_CODE
        AND IM2.KIND_CODE = "120"
        AND IM1.KIND_CODE = "110"
    INNER JOIN PORT AS PT
        ON IM1.PORT_CODE = PT.PORT_CODE
WHERE
    IM1.GROUP_CODE = "120"
    AND 差分 > 0
ORDER BY
    差分 DESC,
    IM1.PORT_CODE DESC;