Use Atlantic;
GO
SELECT O.customer_id AS cust_id, O.orders_id, O.orders_date
, O.orders_sell_price AS sell_price, O.orders_qty AS qty
, (O.orders_sell_price * O.orders_qty) AS line_total
, COUNT(*) OVER(PARTITION BY O.customer_id ORDER BY orders_date) AS cust_orders
, SUM(orders_sell_price* orders_qty) OVER(PARTITION BY O.customer_id ORDER BY orders_date) AS running_total
FROM Orders AS O
ORDER BY O.customer_id, O.orders_date