Write a SELECT statement that answers this question: What is the total quantity purchased for each product within each category? Return these columns: The category_name column from the category table The product_name column from the products table The total quantity purchased for each product with orders in the Order_Items table Use the WITH ROLLUP operator to include rows that give a summary for each category name as well as a row that gives the grand total. Use the IF and GROUPING functions to replace null values in the category_name and product_name columns with literal values if they’re for summary rows.