Create Category tree with PHP and MySQL

recusive-category-tree.php

<?php

/**
 * Creating category Tree using recursion.
 *======================================================*/
function fetchCategoryTree($parent = 0, $spacing = '', $user_tree_array = array())
{
    $sql = "SELECT `cid`, `name`, `parent` FROM `category` WHERE 1 AND `parent` = $parent ORDER BY cid ASC";
    $query = mysql_query($sql);

    if (mysql_num_rows($query) > 0) {
        while ($row = mysql_fetch_object($query)) {
            $user_tree_array[] = array("id" => $row->cid, "name" => $spacing . $row->name);
            $user_tree_array = fetchCategoryTree($row->cid, $spacing . '&nbsp;&nbsp;', $user_tree_array);
        }
    }

    return $user_tree_array;
}


/**
 * Display the category tree in a dropdown list.
 *======================================================*/
$categoryList = fetchCategoryTree(); ?>
<select>
    <?php foreach ($categoryList as $cl): ?>
        <option value="<?php echo $cl["id"] ?>"><?php echo $cl["name"]; ?></option>
    <?php endforeach; ?>
</select>

<?php
/**
 * Displaying Category tree in list format.
 *======================================================*/
function fetchCategoryTreeList($parent = 0, $user_tree_array = array())
{
    $sql = "SELECT `cid`, `name`, `parent` FROM `category` WHERE 1 AND `parent` = $parent ORDER BY cid ASC";
    $query = mysql_query($sql);

    if (mysql_num_rows($query) > 0) {
        $user_tree_array[] = "<ul>";

        while ($row = mysql_fetch_object($query)) {
            $user_tree_array[] = "<li>" . $row->name . "</li>";
            $user_tree_array = fetchCategoryTreeList($row->cid, $user_tree_array);
        }

        $user_tree_array[] = "</ul>";
    }

    return $user_tree_array;
} ?>
<ul>
    <?php
    $res = fetchCategoryTreeList();
    foreach ($res as $r) {
        echo  $r;
    } ?>
</ul>