mysql-thinkphp修改MySQL数据库字段失败

mysqlthinkphpphp

想要修改数据表里的uname和phone字段而其他字段不变，提示失败
$info['uname'] = I('uname');
$info['phone'] = I('phone');
$uid = session('uid');
$res=M('member')->where('uid = "$uid"')->setField($info);