Query does not work - php

Question

I made this code:
Acum, bifeaza materiile pe care le studiaza clasa aleasa:<br />
<form name="servForm" action="<?php $PHP_SELF; ?>" method="post" >
<table border="0">
<?php
$a = 0;
$rezultat = "SELECT id, materie
FROM materii
ORDER BY id";
$rezultat1 = mysql_query($rezultat);
while($plm = mysql_fetch_array($rezultat1))
{
if($a++ %5 == 0) echo "<tr>";
?>
<td align="center"><input type="checkbox" name="checkbox2[]" value="<?php echo $plm['id']; ?>" /></td>
<td style="text-align:left"><?php echo $plm["materie"]; ?> </td>
<?php
if($a %5 == 0) echo "</tr>";
}
?>
</table>
</div>
<br/>
<input type="reset" value="Sterge" /> <input type="submit" value="Salveaza" name="savebtn" />
</form>
<?php
if(isset($_POST['savebtn']))
{
foreach($_POST["checkbox2"] as $loc_id)
{
$query = "INSERT INTO materii_pe_clase(id_scoala,id_clasa,id_materie) VALUES('$scoalalui','$clasalui','$loc_id')"; //aici cauta ! :))
$result5 = mysql_query($query)
or die('eroare');
}//sfarsit foreact
}//sfarsit if isset
Why does the last query not work? p.s. its a school project, so mysql is ok, no need for mysqli. p.p.s I defindet the $scoalalui and $clasalui somwhere a little up the page. but they are not the problem, i tried replacing them with values. the query simply does not work. thanks!
thank you all!
EDIT
VARDUMP for $clasalui and $scoalalui
:
string '1' (length=1)
string '1' (length=1)

Answer 1

Your problem here is that, you have error tool turned off, because PHP should have said, something like this.
Notice: Undefined variable $PHP_SELF"
Since you don't see it, I'd assume that, its a root of your "problem".
PHP_SELF is not a variable, that's a constant. Its not even required here, as by default PHP sends data to its target URL.
I improved readability of your code, so that should work for you now,
<?php
// You want to see all errors? Fine:
error_reporting(E_ALL);
$a = 0;
$rezultat = "SELECT id, materie FROM materii ORDER BY id";
$rezultat1 = mysql_query($rezultat);
// If the form is submitted, this will be executed
if (isset($_POST['savebtn'])) {
foreach($_POST["checkbox2"] as $loc_id) {
$query = "INSERT INTO `materii_pe_clase` (`id_scoala`, `id_clasa`, `id_materie`) VALUES('$scoalalui', '$clasalui', '$loc_id')";
$result = mysql_unbuffered_query($query);
if (!$result){
die(mysql_error());
}
}
// And finally
die('Saved. Thanks');
}
?>
Acum, bifeaza materiile pe care le studiaza clasa aleasa: <br />
<form name="servForm" method="POST">
<table border="0">
<?php while($plm = mysql_fetch_array($rezultat1)) : ?>
<?php if ($a++ %5 == 0) :?>
<tr>
<?php endif; ?>
<td align="center">
<input type="checkbox" name="checkbox2[]" value="<?php echo $plm['id']; ?>" />
</td>
<td style="text-align:left"><?php echo $plm["materie"]; ?> </td>
<?php if($a %5 == 0) : ?>
</tr>
<?php endif; ?>
<?php endwhile; ?>
</table>
<br/>
<input type="reset" value="Sterge" />
<input type="submit" value="Salveaza" name="savebtn" />
</form>