MySQL: ROLLUP

#MySQL #tutorial #course -- ROLLUP, extension of the GROUP BY clause -- produces another row and shows the grand-total (super-aggregate) value SELECT SUM(amount) AS “daily_sales“, order_date FROM transactions GROUP BY order_date WITH ROLLUP; SELECT COUNT(transaction_id) AS “# of orders“, order_date FROM transactions GROUP BY order_date WITH ROLLUP; SELECT COUNT(transaction_id) AS “# of orders“, customer_id FROM transactions GROUP BY customer_id WITH ROLLUP; SELECT SUM(hourly_pay) AS “hourly_pay“, employee_id FROM employees GROUP BY employee_id WITH ROLLUP;