SELECT product_id, SUM(quantity) FROM invoice_items GROUP BY product_id ORDER BY 2 DESC LIMIT 1; SELECT product_id, SUM(quantity) FROM invoice_items GROUP BY product_id ORDER BY 2 LIMIT 1; SELECT product_id, SUM(quantityprice) FROM invoice_items GROUP BY product_id ORDER BY 2 DESC LIMIT 1; SELECT product_id, SUM(quantityprice) FROM invoice_items GROUP BY product_id ORDER BY 2 LIMIT 1;