Task: Text to Code
Input (English): Give me the name of the customer who ordered the most items in total.
Output (English): 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