Show all product names
select product_name from products
Also show the quantity ordered for each order of a product.
select t2.product_name, t1.product_quantity from order_items as t1 join products as t2 on t1.product_id = t2.product_id
What is the total quantity ordered for each product name?
select t2.product_name, sum(t1.product_quantity) from order_items as t1 join products as t2 on t1.product_id = t2.product_id group by t2.product_name