SELECT SUM(goods_total) AS Total_Amount  FROM orders
WHERE order_placed_date >= date_sub(current_date, INTERVAL 1 MONTH);

SELECT SUM(goods_total) AS Total_Amount  FROM orders
WHERE SUBSTRING(o.order_placed_date FROM 1 FOR 7) =   SUBSTRING(CURRENT_DATE - INTERVAL 1 MONTH FROM 1 FOR 7)