SELECT
    PO.PORT_CODE AS 港コード,
    PO.PORT_NAME AS 港名,
    IM.AMT AS 入国者数,
    OUT.AMT AS 出国者数,
    IM.AMT - OUT.AMT AS 差分
FROM
    IMMIGRATION AS IM
        INNER JOIN PORT AS PO
            ON PO.PORT_CODE = IM.PORT_CODE
        INNER JOIN IMMIGRATION AS OUT
            ON OUT.PORT_CODE = IM.PORT_CODE
            AND OUT.KIND_CODE = "120"
WHERE
    IM.KIND_CODE = "110"
    AND IM.AMT > OUT.AMT
ORDER BY
    差分 DESC,
    港コード DESC