1. Code a function named Get_balance_due that accepts order_id and returns balance due. Include the following test statement in your script file.

SELECT First_name, Last_name, get_balance_due(orders.order_id) FROM customers, Orders, order_lines WHERE customers.customer_id= orders.customer_id and orders.order_id=order_lines.order_id and To_Char (order_date, 'mm/dd/yyyy') = 09/30/2002' Group By First_name, Last_name, get_balance_due(orders.order_id);