Table schema:
CREATE TABLE Products (product_name VARCHAR, product_id VARCHAR); CREATE TABLE Order_items (product_quantity INTEGER, product_id VARCHAR)

Question: Show all product names and the total quantity ordered for each product name.
SQL: 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