SELECT
    order_date,
    region,
    revenue,

    SUM(revenue) OVER (
        PARTITION BY region
        ORDER BY order_date
        ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW
    ) AS running_total,

    revenue - LAG(revenue) OVER (
        PARTITION BY region ORDER BY order_date
    ) AS vs_previous,

    DENSE_RANK() OVER (
        PARTITION BY region ORDER BY revenue DESC
    ) AS rank_in_region

FROM orders
ORDER BY region, order_date;