Strukturierung komplexer mehrstufiger Abfragen mit CTEs

WITH RegionalSales AS (
    SELECT
        region_id,
        SUM(total_amount) AS total_sales
    FROM sales_orders
    GROUP BY region_id
),
AverageSales AS (
    SELECT AVG(total_sales) AS avg_regional_sales
    FROM RegionalSales
)
SELECT
    r.region_id,
    r.total_sales
FROM RegionalSales r, AverageSales a
WHERE r.total_sales > a.avg_regional_sales;