Question: What are the name and phone of the customer with the most ordered product quantity?
SQL: SELECT  T1.customer_name ,  T1.customer_phone FROM customers AS T1 JOIN customer_orders AS T2 ON T1.customer_id  =  T2.customer_id JOIN order_items AS T3 ON T3.order_id  =  T2.order_id GROUP BY T1.customer_id ORDER BY sum(T3.order_quantity) DESC LIMIT 1