Tell me the customer name for each order.
select t1.customer_name from customers as t1 join customer_orders as t2 on t1.customer_id = t2.customer_id join order_items as t3 on t2.order_id = t3.order_id
What is the total quantity ordered by each customer?
select sum(t3.order_quantity) from customers as t1 join customer_orders as t2 on t1.customer_id = t2.customer_id join order_items as t3 on t2.order_id = t3.order_id group by t1.customer_name
Give me the name of the customer who ordered the largest quantity in total.
select t1.customer_name from customers as t1 join customer_orders as t2 on t1.customer_id = t2.customer_id join order_items as t3 on t2.order_id = t3.order_id group by t1.customer_name order by sum(t3.order_quantity) desc limit 1