SELECT
    IM.PORT_CODE AS 港コード
    ,PORT.PORT_NAME AS 港名
    ,SUM(CASE WHEN KIND_CODE = 110 THEN AMT END) AS 入国者数
    ,SUM(CASE WHEN KIND_CODE = 120 THEN AMT END) AS 出国者数
    ,SUM(CASE WHEN KIND_CODE = 110 THEN AMT END) - SUM(CASE WHEN KIND_CODE = 120 THEN AMT END) AS 差分
FROM
    IMMIGRATION AS IM
        INNER JOIN PORT
            ON IM.PORT_CODE = PORT.PORT_CODE
WHERE
    GROUP_CODE = 120
GROUP BY
    IM.PORT_CODE
HAVING
    差分 > 0
ORDER BY
    差分 DESC
    ,IM.PORT_CODE DESC