require_once(__DIR__."/../includes/config.php");
require_once(__DIR__."/../includes/functions.php");
startSession();
define('DSN','mysql:host=localhost;dbname=solvedesktop');
define('USERNAME' , 'root');
define('PASSWORD' , '');

try {
    $DB = new PDO(DSN, USERNAME, PASSWORD);
} catch(PDOException $e) {
    echo $e->getMessage();
}

try {
    if(isset($_SESSION["id"])){
        $sql = "SELECT * FROM drop_down WHERE published = 1 AND loggedin = 1";
        $result = $DB->query($sql);
        $row_count = $result->rowCount();
        if($row_count){
            $rows = $result->fetchAll(PDO::FETCH_ASSOC);
        }
    } else {
        $sql = "SELECT * FROM drop_down WHERE published = 1 AND loggedin = 0";
        $result = $DB->query($sql);
        $row_count = $result->rowCount();
        if($row_count){
            $rows = $result->fetchAll(PDO::FETCH_ASSOC);
        }
    }
catch(PDOException $e) {
    echo $e->getMessage();
    }
}

<?php
    $items = $rows;
    $id = '';
    echo "<ul class ='multidrop'>";
    foreach($items as $item){
        if($item['parent_id'] == 0){
            echo "<li><a href=../home/view.php?id=".$item['id'].">".$item['title']."</a>";
            $id = $item['id'];
            sub($items, $id);
            echo "</li>";
        }
    }
    echo "</ul>";
    function sub($items, $id){
        echo "<ul>";
        foreach($items as $item){
            if($item['parent_id'] == $id){
                echo "<li><a href=../home/view.php?id=".$item['id'].">".$item['title']."</a>";
                sub($items, $item['id']);
                echo "</li>";
            }
        }
        echo "</ul>";
    }
?>