Write a SQL query that returns the total quantity of each product ordered by each customer.
About this solution: The candidate's solution does not demonstrate a level of completeness and does not solve the problem. The candidate's approach is not clear.
Write a SQL query that returns the total quantity of each product ordered by each customer.
About this solution: The candidate's solution correctly returns the total quantity of each product ordered by each customer. The solution uses the GROUP BY clause to group the customer and product IDs together, and then uses the SUM function to calculate the total quantity for each group. The solution is clear and concise.