Modify the query of part 6C to get the total order quantities per customer (sum over all the orders for each customer). Should you use both first and last name? What would happen if you use only the first name and two customers have the same first name?

Now generalize the query for all customers and check how the number of returned records changes based on whether you are using only the first, only the last or both first and last names.

And this is my code from the previous question.

SELECT c.CUSTOMER_LAST_NAME, NVL(od.ORDER_QTY,0) FROM ORDER_DETAILS od INNER JOIN ORDERS o ON o.ORDER_ID = od.ORDER_ID INNER JOIN CUSTOMERS c ON c.CUSTOMER_ID = o.CUSTOMER_ID WHERE c.CUSTOMER_LAST_NAME = 'Blanca';