Find the total quantity order for each product.
select sum(order_quantity) from order_items group by product_id
What is the id of the product whose total order quantity is the largest?
select product_id from order_items group by product_id order by sum(order_quantity) limit 1
What are the name and ID of that product?
select t2.product_details, t2.product_id from order_items as t1 join products as t2 on t1.product_id = t2.product_id group by t1.product_id order by t1.order_quantity limit 1