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