Tříúrovňové menu v PHP + MySQL

-
CREATE TABLE IF NOT EXISTS `menu` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `popisek` text NOT NULL,
  `id_nadrazena` int(11) NOT NULL,
  `uroven` int(11) NOT NULL,
  `top` int(11) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 AUTO_INCREMENT=16 ;

INSERT INTO `menu` (`id`, `popisek`, `id_nadrazena`, `uroven`, `top`) VALUES
(1, 'Chorvatsko', 1, 0, 1),
(2, 'Slovensko', 2, 0, 2),
(3, 'Drvenik', 1, 1, 1),
(4, 'Katarina', 3, 2, 1),
(5, 'Kuka', 3, 2, 1),
(6, 'Apollon', 3, 2, 1),
(7, 'Camp dole', 1, 1, 1),
(8, 'Karavan', 7, 2, 1),
(9, 'Chata', 7, 2, 1),
(10, 'Stan', 7, 2, 1),
(11, 'Bratislava', 2, 1, 2),
(12, 'Apartman', 11, 2, 2),
(13, 'Hotel', 7, 2, 1),
(15, 'Ňuf', 3, 2, 1);

$sql=dibi::query('SELECT * FROM menu ORDER BY top ASC');
?>
<table>
<thead>
    <th>Položky</th>
    <th>Akce</th>
</thead>
<?php
while ($row = $sql->fetch()){
    if($row['uroven']==0){
        $oddel="";
    }
    elseif($row['uroven']==1){
        $oddel="&nbsp;&nbsp;";
    }
    else{
        $oddel="&nbsp;&nbsp;&nbsp;&nbsp;";
    }

?>
<tr>
    <td><?php echo $oddel; echo $row['popisek'];?></td>
    <td><a href="?page=edit&id=<?php echo $row['id'];?>"><img src="../css/img/upravit.fw.png" /></a>
    <a href="?page=del&id=<?php echo $row['id'];?>"><img src="../css/img/vymazat.fw.png" /></a></td>
</tr>
<?php
}
?>

if($page=="add"){
    $sql=dibi::query('SELECT * FROM menu WHERE [uroven] < %i', "2");
    ?>
    <form action="?page=add_script" method="POST">
    <input type="text" name="jmeno" placeholder="Název položky" />
    <label for="uroven">Úroveň:</label>
    <select size="3" name="uroven" id="uroven">
        <option value="0">-- Vyberte --</option>
        <option value="0">První</option>
        <option value="1">&nbsp;&nbsp;Druhá</option>
        <option value="2">&nbsp;&nbsp;&nbsp;&nbsp;Třetí</option>
    </select>
    <select size="1" name="id_nadrazena">
    <option value="0">-- Vyberte --</option>
    <?php
    while($row = $sql->fetch()){?>
    
        <option value="<?php echo $row['id'];?>"><?php echo $row['popisek'];?></option>
        <?php
    }
    ?>
    </select>
    <input type="submit" class="btn btn-success btn-sm" value="Přidat novou položku" />
    </form>
<?php
}
elseif($page=="add_script"){
    if($_POST['uroven']==0){
        $result = dibi::query('SELECT id FROM menu ORDER BY id DESC LIMIT 1');
        $last = $result->fetchSingle();
        $id_nadrazena=($last+1);
        $top=$id_nadrazena;
    }
    elseif($_POST['uroven']==1){
        $id_nadrazena=$_POST['id_nadrazena'];
        $result = dibi::query('SELECT id_nadrazena FROM menu WHERE [id] = %i', $id_nadrazena);
        $id = $result->fetchSingle();
        $top=$id;
    }
    else{
        $id_nadrazena=$_POST['id_nadrazena'];
        $result = dibi::query('SELECT id_nadrazena FROM menu WHERE [id] = %i', $id_nadrazena, 'and [uroven] = %i', "1");
        $id = $result->fetchSingle();
        $top=$id;
    }
   $arr = array(
    'popisek'  => $_POST['jmeno'],
    'id_nadrazena' => $id_nadrazena,
    'uroven' => $_POST['uroven'],
    'top' => $top
    );
    dibi::query('INSERT INTO [menu]', $arr);
    header("Location: menu.php?message_type=complete&message=Položka menu přidána");
}