Codeigniter/Postgresql:致命错误:在非对象上调用成员函数num_rows(）

这件事困扰了我几天，我一直没能解决它。我有这个注册表单。当提交这个表格时，这个错误不断出现，发生这种情况的原因是注册详细信息没有插入数据库。

我使用Postgresql作为数据库系统。但数据并没有被插入。我真的很沮丧。我会在下面发布我的模型，控制器，如果需要什么，请告诉我。

控制器：

    function register()
{
    //set validation rules
    $this->form_validation->set_rules('customer_name', 'Customer Name', 'trim|required|xss_clean');
    $this->form_validation->set_rules('address1', 'Address 1', 'trim|required|xss_clean');
    $this->form_validation->set_rules('address2', 'Address 2', 'trim|required|xss_clean');
    $this->form_validation->set_rules('city', 'City', 'trim|required|xss_clean');
    $this->form_validation->set_rules('state', 'State', 'trim|required|xss_clean');
    $this->form_validation->set_rules('country', 'Country', 'trim|required|xss_clean');
    $this->form_validation->set_rules('phone', 'Phone', 'trim|required|xss_clean|is_numeric');
    $this->form_validation->set_rules('mobile', 'Mobile', 'trim|required|xss_clean|is_numeric');
    $this->form_validation->set_rules('email', 'Email', 'trim|required|valid_email|is_unique[gkb_users.email]');
    $this->form_validation->set_rules('username', 'Username', 'trim|required|is_unique[gkb_users.username]');
    $this->form_validation->set_rules('password', 'Password', 'trim|required|md5');
    $this->form_validation->set_rules('confpassword', 'Confirm Password', 'trim|required|matches[password]|md5');
    //validate form input
    if ($this->form_validation->run() == FALSE)
    {
    //fails
    $this->loadHeader($this);
    //load sidebar
    $this->loadSidebar($this);
    //load middle content
    $this->load->view('register_view'); 
    //load footer
    $this->loadFooter($this);
    }
    else
    {
        //insert the user registration details into database
        $data = array(
            'cust_name' => $this->input->post('customer_name'),
            'address1' => $this->input->post('address1'),
            'address2' => $this->input->post('address2'),
            'city' => $this->input->post('city'),
            'state_code' => $this->input->post('state'),
            'country_code' => $this->input->post('country'),
            'phone' => $this->input->post('phone'),
            'mobile' => $this->input->post('mobile'),
            'email' => $this->input->post('email'),
            'username' => $this->input->post('username'),
            'password' => $this->input->post('password'),
        );
        // insert form data into database
        if ($this->user_model->insertUser($data))
        {
            // send email
            if ($this->user_model->sendEmail($this->input->post('email')))
            {
                // successfully sent mail
                $this->session->set_flashdata('msg','<div class="alert alert-success text-center">You are Successfully Registered! Please confirm the mail sent to your Email-ID!!!</div>');
                redirect('user/register');
            }
            else
            {
                // error
                $this->session->set_flashdata('msg','<div class="alert alert-danger text-center">Oops! Error.  Please try again later!!!</div>');
                redirect('user/register');
            }
        }
        else
        {
            // error
            $this->session->set_flashdata('msg','<div class="alert alert-danger text-center">Oops! Error.  Please try again later!!!</div>');
            redirect('user/register');
        }
    }
}

型号：

    function insertUser($data)
{
    return $this->db->insert('users', $data);
}

如果我能解决这个问题，我将非常感激。感谢

编辑：

    public function checkfrontendUser($username,$passwd)
{
    $sql = "
        SELECT * FROM users
        WHERE (
                    `username` = '".$username."'
                    OR
                    `email` = '".$username."'
              )
              AND `password` = '".$passwd."'
    ";      
    $result = $this->db->query($sql);
    if ($result->num_rows() > 0)
    {
        return $result->result_array();
    }       
    return FALSE;
}