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