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