how to retrieve value from database using codeigniter

Question

Controller

public function index()
{

    $config["base_url"] = base_url() . "index.php/admin_requirements/index";
    $config["total_rows"] = $this->admin_requirements_full->record_count();
    $config['per_page'] = 5;
    $this->pagination->initialize($config);
    $page = $this->uri->segment(3);

    $data['results'] = $this->admin_requirements_full->display($config["per_page"], $page);
    $data['links'] = $this->pagination->create_links();

    $session_data = $this->session->userdata('logged_in');
    $data['username'] = $session_data['username'];

    $this->load->view('adminpanel/header',$data);
    $this->load->view('adminpanel/menubar');
    $this->load->view('adminpanel/footer');
}

Model

function display($limit, $start)
{

    $this->db->limit($limit, $start);
    $query  =   $this->db->get('db_requirements');
    return $query->result();
}

public function record_count() 
{
    return $this->db->count_all("db_requirements");
}

View

<?php
    foreach($results as $data) 
    {
?>
    <tr align="center">
        <td height="29"><?php echo $data->id; ?></td>
        <td><?php echo $data->cat_id; ?></td>
        <td><?php echo $data->subcat_id; ?></td>
        <td><?php echo $data->city; ?></td>
        <td><?php echo $data->email_id; ?></td>
        <td><?php echo $data->phone; ?></td>
        <td><?php echo $data->publish; ?></td>
        <td>Delete</td>
    </tr>
<?php
    }
?>
</table>
<p class="pages">Pages : <?php echo $links; ?></p>

Result

[Sl.No] [category] [subcategory]
1 1 1
2 3 1

In the above result CATEGORY and SUBCATEGORY fields are in numerals. The actual value of these numbers are stored in another database table.

My question is , how can i retreive actual value for the above numbers.

My CATEGORY and SUBCATEGORY databse are given below.

// db_bus_category

id, item

// db_bus_subcategory

id, cat_id, subcat_id, item

Answer 1

If you need to get values from other tables you will need to use an SQL JOIN. A cursory glance at the active record section of the codeigniter documentation shows a function $this->db->join();

https://ellislab.com/codeigniter/user-guide/database/active_record.html