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
JOIN
    IMMIGRATION AS I2
USING
    (PORT_CODE)
JOIN
    GRP AS G
USING
    (GROUP_CODE)
JOIN
    PORT AS P
USING
    (PORT_CODE)
WHERE
    I1.GROUP_CODE = 120
    AND I1.KIND_CODE = 110
    AND I2.KIND_CODE = 120
    AND I1.AMT > I2.AMT
ORDER BY
    I1.AMT - I2.AMT DESC,
    PORT_CODE DESC