每个子类别的类别都在重复

Question

I am showing categories in Menu. Some categories have subcategories.

function for getting parent categories

function get_parent_category(){
        $query="select * from blog_categories where parent_id=0 
                ORDER BY 
                CASE id 
                    WHEN '2' THEN 1 
                    WHEN '1' THEN 2 
                    WHEN '3' THEN 3
                    ELSE id 
                END";
        $rows=array();
        $result=$this->query($query);
        while($row=$this->fetch_array($result)){
            $row['url']=$this->get_cat_url($row);
            $rows[]=$row;
        }
        return $rows;
    }

Function for subcategories

function get_child_category(){
        $query="select * from blog_categories where parent_id!=0";
        $rows=array();
        $result=$this->query($query);
        while($row=$this->fetch_array($result)){
            $row['url']=$this->get_cat_url($row);
            $rows[]=$row;
        }
        return $rows;
}

Showing on the page like this:

<ul class="nav navbar-nav">
    <li><a href="<?php echo BASE_URL ?>">Home</a></li>
    <?php 
         foreach($this->parent_category as $cat){
            foreach($this->child_category as $child_cat){
                if($cat['id']==$child_cat['parent_id']){
    ?>
        <li class="dropdown">
            <a class="dropdown-toggle" data-toggle="dropdown" href="#"><?php echo $cat['name'];?>
            <span class="caret"></span></a>
            <ul class="dropdown-menu">
                <li><a href="#"><?php echo $child_cat['name']?></a></li>
            </ul>
        </li>
    <?php
                }elseif($cat['parent_id']==0){
    ?>
        <li><a href="<?php echo $cat['url']?>"><span><?php echo $cat['name'];?></span></a></li>
    <?php
                }
     ?>

    <?php }}?>

Output and Problem

The Main category circle in red color is seerah which has two subcategories. showing two times for first one in drop down one subcategory and for second time second subcategory is showing.

DB structure

What i wants:

I wants to show each subcategories under each parent category without repetition , how can i achieve this?

Answer 1

Here is how i handled the problem

<?php 
         foreach($this->parent_category as $cat){
             $html = '';
             foreach($this->child_category as $child_cat){
                if($cat['id']==$child_cat['parent_id']){
                    $html .=  '<li><a href="'.$child_cat['url'].'">' . $child_cat['name'] . '</a></li>';
                    // here is all child categories are saved in var.
                }
             }

             if ($html == '') {
    ?>
                <li><a href="<?php echo $cat['url']?>"><span><?php echo $cat['name'];?></span></a></li>
    <?php
            } else {
    ?>
            <li class="dropdown">
                <a class="dropdown-toggle" data-toggle="dropdown" href="#"><?php echo $cat['name'];?>
                <span class="caret"></span></a>
                <ul class="dropdown-menu">
                    <?php echo $html; ?> // here is displayed under parent category
                </ul>
            </li>
    <?php
            }
        }
    ?>

Output