Counting Related Records with JOIN and GROUP BY

SELECT
    c.customer_id,
    c.customer_name,
    COUNT(o.order_id) AS total_orders
FROM
    customers c
LEFT JOIN
    orders o ON c.customer_id = o.customer_id
GROUP BY
    c.customer_id, c.customer_name
HAVING
    COUNT(o.order_id) > 0
ORDER BY
    total_orders DESC;

How it works: This query joins the `customers` table with the `orders` table to count the total number of orders placed by each customer. The `LEFT JOIN` ensures that all customers are considered, even those without orders. `GROUP BY` aggregates the counts for each unique customer. The `HAVING` clause then filters these groups to only include customers who have placed at least one order, and the results are ordered by the total number of orders.