php debugging

PHP kode 

 <?php
     $conn = new mysqli('localhost','','','');
         //$conn = new mysqli('localhost','root','','');
     $query = "SELECT filename,title,id FROM debug_pictures";
     $showPictures = $conn->query($query);
     
     if(isset($_POST["id"])){
         $title = $_POST["title"];
         $id = $_POST["id"];
         $sql = "UPDATE debug_pictures SET title='$title' WHERE id='$id'";
         $conn->query($sql);
     }
 ?>
     
     
 <?php if(isset($_GET["id"])){ ?>
     <form action="index.php" method="POST">
         <table cellspacing="0" cellpadding="0">
             <tr>
                 <td style="width: 50px;">Titel</td>
                 <td><input type="text" id="title" name="title" /></td>
             </tr>
             <tr>
                 <td></td>
                 <td><input type="submit" name="submit" id="submit" value="Gem" /></td>
             </tr>
         </table>
     </form><?php 
 } else{ 
     while($row = $showPictures->fetch_assoc()){ ?>
         <a href="?id=<?php echo $row['id']; ?>"><?php echo $row['title']; ?></a><br /><?php
     }
 } ?>

SQL kode 

 SET SQL_MODE="NO_AUTO_VALUE_ON_ZERO";
 
 CREATE TABLE IF NOT EXISTS `debug_pictures` (
   `id` int(11) NOT NULL auto_increment,
   `filename` varchar(255) NOT NULL,
   `title` varchar(255) NOT NULL,
   PRIMARY KEY  (`id`)
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ;
 
 INSERT INTO  `anderss_wi4_sde_dk`.`debug_pictures` (`id` ,`filename` ,`title`)
 VALUES ( NULL ,  '1.jpg',  'Billede 1'), 
 ( NULL ,  '2.jpg',  'Billede 2' ), 
 ( NULL ,  '3.jpg',  'Billede 3' ), 
 ( NULL ,  '4.jpg',  'Billede 4' ), 
 ( NULL ,  '5.jpg',  'Billede 5' );