UCenter修改用户名无效的解决方法

function onedit() {
   $uid = getgpc('uid');
   $status = 0;
   if(!$this->user['isfounder']) { //判断是否受保护用户
     $isprotected = $this->db->result_first("SELECT COUNT(*) FROM ".UC_DBTABLEPRE."protectedmembers WHERE uid = '$uid'");
     if($isprotected) {
        $this->message('user_edit_noperm');
     }
   }

   if($this->submitcheck()) { //判断是否提交更新
     $username = getgpc('username', 'P');
     $newusername = getgpc('newusername', 'P');
     $password = getgpc('password', 'P');
     $email = getgpc('email', 'P');
     $delavatar = getgpc('delavatar', 'P');
     $rmrecques = getgpc('rmrecques', 'P');
     $sqladd = '';
     if($username != $newusername) { //是否更新用户名
        if($_ENV['user']->get_user_by_username($newusername)) {
          $this->message('admin_user_exists');
        }
        $sqladd .= "username='$newusername', ";
        $this->load('note');
        $_ENV['note']->add('renameuser', 'uid='.$uid.'&oldusername='.urlencode($username).'&newusername='.
urlencode($newusername));//保存记录
     }
     if($password) { //密码是否更新
        $salt = substr(uniqid(rand()), 0, 6);
        $orgpassword = $password;
        $password = md5(md5($password).$salt);
        $sqladd .= "password='$password', salt='$salt', ";
        $this->load('note');
        $_ENV['note']->add('updatepw', 'username='.urlencode($username).'&password=');//保存记录
     }
     if($rmrecques) { //验证问答
        $sqladd .= "secques='', ";
     }
     if(!empty($delavatar)) { //删除头像
        $_ENV['user']->delete_useravatar($uid);
     }

     $this->db->query("UPDATE ".UC_DBTABLEPRE."members SET $sqladd email='$email' WHERE uid='$uid'");
     $status = $this->db->errno() ? -1 : 1;
   }    
   $user = $this->db->fetch_first("SELECT * FROM ".UC_DBTABLEPRE."members WHERE uid='$uid'");
   $user['bigavatar'] = '';
   $user['bigavatarreal'] = '';
   $this->view->assign('uid', $uid);
   $this->view->assign('user', $user);
   $this->view->assign('status', $status);
   $this->view->display('admin_user');
}