2022-12-17：订单最多的客户。以下数据，结果输出3。请问sql语句如何写？
DROP TABLE IF EXISTS `orders`;
CREATE TABLE `orders` (
`order_number` int(11) NOT NULL,
`customer_number` int(11) NOT NULL,
PRIMARY KEY (`order_number`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

INSERT INTO `orders` VALUES ('1', '1');
INSERT INTO `orders` VALUES ('2', '2');
INSERT INTO `orders` VALUES ('3', '3');
INSERT INTO `orders` VALUES ('4', '3');