我如何添加特定的css id与php或javascript父菜单

我们正在开发一个菜单，从mysql中获取数据。

DB结构;

id  | name      | link      |   parent_id   
-----------------------------------------
1   | Home      | p.php     |   0
2   | Portfolio | p.php     |   0
3   | Projects  | p.php     |   0
4   | Contact   | p.php     |   0
5   | Web Design| p.php     |   2
6   | Grap. Desg| p.php     |   2
.
.
.
14  | Quote     | p.php     |   6 
.
-----------------------------------------

<?php
$baseUri = $_SERVER['PHP_SELF'];
$menuHtml='';
function createMenu($parentId){
    global $baseUri;
    global $menuHtml;
    global $db;
    $query = $db->prepare('SELECT * FROM menu_options WHERE `parent_id` = ?');
    $query->bindParam(1, $parentId, PDO::PARAM_INT);
    $query->execute();
    $rowCount = $query->rowCount();
    if ($rowCount == 0) return;
    if ($parentId == 0)
        $menuHtml.="<ul id='"menu'">'r'n";
    else
    $menuHtml.='<ul>';
    while($row = $query->fetch(PDO::FETCH_OBJ))
    {
        $menuHtml.='<li><a href="'.$row->url.'">'.$row->name.'</a>';
        createMenu($row->id);
        $menuHtml.='</li>';
    }   
$menuHtml.='</ul>';
return $menuHtml;
}
echo createMenu(0);
?>

和HTML Result;

<ul>
    <li><a href="index.php">HOMEPAGE</a></li>
    <li class=""><a href="articles.php">CORPORATE</a>
        <ul style="visibility: hidden; display: none;">
            <li><a href="article.php?i=1">About Us</a></li>
            <li><a href="article.php?i=1">Mission Vision</a></li>
            <li><a href="project2.php">Company Tag</a></li>
            <li><a href="project2.php">Production</a></li>
        </ul>
     </li>
     <li class=""><a href="projects.php">PRODUCTS</a>
        <ul style="visibility: hidden; display: none;">
            <li><a href="project4.php">Meltblown</a></li>
            <li><a href="support.php">Spunbond</a></li>
            <li><a href="quote.php">Sms &amp; Smms</a></li>
            <li><a href="">Composites</a></li>
        </ul>
     </li>
     <li><a href="articles.php?i=1">QUALITY</a></li>
     <li><a href="articles.php?i=1">NEWS</a></li>
     <li><a href="gallery.php">GALLERY</a></li>
     <li><a href="contact.php">CONTACT</a></li>
</ul>

我们认为$baseUri = $_SERVER['PHP_SELF'];的某种if else语句，但它不能解决我们的问题。我们想在PHP中添加一个css类。如果我们在index.php菜单必须像;

<ul>
        <li><a class="current" href="index.php">HOMEPAGE</a></li>
        <li class=""><a href="articles.php">CORPORATE</a>

我们有子菜单，这些子菜单有父菜单。我们只希望为parent_id = 0添加特定的CSS类。如果子菜单的父菜单大于0，则应该查找父菜单的父菜单。这有点复杂，我们很困惑