How to create dynamic navigation menu select from database using Codeigniter?

I've been trying to find the solution for creating a dynamic navigation menu store in database using Codeigniter. But till now I can't solve my problem and I really don't understand how to create this feature I try to create below code but I can show only menu without sub menu. As in the view I can't only select menu but can't with sub menus. I'm really don't understand how to make the conditional for create sub menus Because I have to compared parent with menus ID if I found the parent equal to menu ID I will show the drop down for current that menu But it is fail for me

Here is my View

<div class="navbar-collapse collapse">
    <ul class="nav navbar-nav">
       <li><a>some menu retrieve from DB </a></li>
           <li class="dropdown megamenu-fullwidth"> 
              <a data-toggle="dropdown" class="dropdown-toggle">title</a>
              <ul class="dropdown-menu"> 
                <li class="megamenu-content">
                 <ul class="col-lg-2 col-sm-2 col-md-2">
                   <li class="no-border"><p><strong>Head</strong></p></li>
                   <li><a href="#">Descript<br></a></li>
                 </ul> 
               </li> 
            </ul>
        </li>
       <?PHP endif; ?>
      <?PHP endforeach; ?>
 </ul>    
</div>

Here is Controller

$this->data['menus'] =  $this->nav_m->menus(); 

Here is model

 public function menus() {
        $this->db->select("*");
        $this->db->from("nav"); 
        $this->q = $this->db->get();
        if ($this->q->num_rows() > 0) {
           return $this->q->result_array();
        }
    }

Here is my navigation which I used Var_dump() from DB

array (size=7)
  0 => 
    array (size=9)
      'id' => string '1' (length=1)
      'uid' => string '0' (length=1)
      'text' => string 'title1' (length=6)
      'link' => string 'menus1' (length=6)
      'show_condition' => string '1' (length=1)
      'parent' => string '0' (length=1)
      'class' => string '' (length=0)
      'data' => string '' (length=0)
      'des' => string '' (length=0)
  1 => 
    array (size=9)
      'id' => string '2' (length=1)
      'uid' => string '0' (length=1)
      'text' => string 'title2' (length=6)
      'link' => string 'menus2' (length=6)
      'show_condition' => string '1' (length=1)
      'parent' => string '2' (length=1)
      'class' => string '1' (length=1)
      'data' => string '' (length=0)
      'des' => string '' (length=0)
  2 => 
    array (size=9)
      'id' => string '3' (length=1)
      'uid' => string '0' (length=1)
      'text' => string 'title3' (length=6)
      'link' => string 'menu3' (length=5)
      'show_condition' => string '1' (length=1)
      'parent' => string '2' (length=1)
      'class' => string '' (length=0)
      'data' => string '' (length=0)
      'des' => string '' (length=0)
  3 => 
    array (size=9)
      'id' => string '4' (length=1)
      'uid' => string '0' (length=1)
      'text' => string 'Sub1' (length=4)
      'link' => string 'menu4' (length=5)
      'show_condition' => string '1' (length=1)
      'parent' => string '2' (length=1)
      'class' => string '' (length=0)
      'data' => string '' (length=0)
      'des' => string '' (length=0)
  4 => 
    array (size=9)
      'id' => string '5' (length=1)
      'uid' => string '0' (length=1)
      'text' => string 'sub2' (length=4)
      'link' => string 'hhhhhhhhhhhh' (length=12)
      'show_condition' => string '1' (length=1)
      'parent' => string '2' (length=1)
      'class' => string '' (length=0)
      'data' => string '' (length=0)
      'des' => string '' (length=0)
  5 => 

Please help