SELECT
    I1.PORT_CODE AS '港コード',
    P.PORT_NAME AS '港名',
    I1.AMT AS 入国者数,
    I2.AMT AS 出国者数,
    (I1.AMT - I2.AMT) AS '差分'
FROM
    IMMIGRATION AS I1
    INNER JOIN IMMIGRATION AS I2
        ON I1.PORT_CODE = I2.PORT_CODE
        AND I1.GROUP_CODE = I2.GROUP_CODE
        AND I2.KIND_CODE = '120'
    INNER JOIN PORT AS P
        ON I1.PORT_CODE = P.PORT_CODE
WHERE
    I1.GROUP_CODE = '120'
    AND I1.KIND_CODE = '110'
    AND 差分 > 0
ORDER BY
    差分 DESC,
    I1.PORT_CODE DESC