generate un-ordered list menu from php, mysql

Hi,
I need to convert categories table into un-ordered list menu.

table:
categories(id int, name varchar(255), parent int);
id name parent
1 n1 0
2 n2 1
3 n3 1
4 n4 2
5 n5 4
6 n6 0

I tried using code:

while ( $row = mysqli_fetch_assoc($query) ) {
$menu_array[$row['category_id']] = array('name' => $row['category_name'],'parent' => $row['parent_category_id']);
}

function generate_menu($parent) {
$has_childs = false;
global $menu_array;
foreach($menu_array as $key => $value) {
if ($value['parent'] == $parent) {
if ($has_childs === false) {
$has_childs = true;
echo '<ul>';
}
echo '<li><a href="#">' . $value['name'] . '</a>';
generate_menu($key);
echo '</li>';
}
}
if ($has_childs === true) echo '</ul>';
}

generate_menu(0);


I need to get in this format.
<ul id="jsddm">
<li><a href="#">JavaScript</a>
<ul>
<li><a href="#">Drop Down Menu</a></li>
<li><a href="#">jQuery Plugin</a></li>
</ul>
</li>
<li><a href="#">Effect</a>
<ul>
<li><a href="#">Slide Effect</a></li>
</ul>
</li>
<li><a href="#">Navigation</a></li>
</ul>

help would be appreciated.

 

function menu($parent=0)
{
        $shown = array();
        $result = mysql_query("SELECT c.* , (SELECT GROUP_CONCAT(x.id) FROM categories as x WHERE x.parent = c.id ORDER BY x.id ASC) as children FROM categories as c WHERE c.parent = '".$parent."' AND c.id != '".$parent."' ORDER BY c.id ASC");
        if(mysql_num_rows($result) > 0)
        {
            while($row = mysql_fetch_array($result))
            {
                echo '  <li>
                            <a href="#">'.$row['name'].'</a>';
                
                if(!is_null($row['children']))
                {
                    echo '  <ul>';    
                    menu($row['id']);
                    echo '  </ul>';
                }
                
                echo '  </li>';
            }                
        }
}
    
echo '<ul id="jsddm">';
menu();
echo '</ul>';

PHP: