text: CREATE TABLE `qr` (
  	`id` bigint unsigned NOT NULL AUTO_INCREMENT,
  	`qr_code` varchar(255)  NOT NULL DEFAULT '' COMMENT '验证码',
  	`auth_count` tinyint(3) unsigned NOT NULL DEFAULT '0' COMMENT '验证次数',
  	`create_time` timestamp NULL DEFAULT CURRENT_TIMESTAMP,
  	`update_time` timestamp NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  	PRIMARY KEY (`id`)
  ) ENGINE=InnoDB  DEFAULT CHARSET=utf8mb4;