$viewlist = Db::view('city','id,cityname')
->view('city',['cityname'=>'city_cityname'],'city.id=city.cityid','LEFT')
->order('city.id DESC')
->select();

错误的SQL: SELECT `city`.`id`,`city`.`cityname`,`city`.`cityname` AS `city_cityname` FROM `w_city` `city` LEFT JOIN `w_city` `city` ON `city`.`id`=`city`.`cityid` ORDER BY city.id DESC