Task: Text to Code
Input (English): SQL: SELECT product_name , Sum ( * ) FROM Products GROUP BY product_name
Feedback: Calculate the total of rows that correspond to each value of product quantity.
Output (English): 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