Uppdatera MySQL-databas via XML-dokument, hjälp???

<?php
require ('db_connect.php');

//Man kan använda tre funktioner, kallade get_tag_match_string, get_tag_contents och
//get_tag_contents_array för att extrahera innehållet i ett XML-element, som finns lagrat i en sträng

//get_tag_match_string: returns a match string for
//finding a tag, to be used with preg_match

function get_tag_match_string($tagName)
{
$matchString = "/<$tagName";
$matchString .= "[\s]*>(.*?)<\/$tagName";
$matchString .= "[\s]*>/s";

return $matchString;
}

// get_tag_contents: returns the contents of the element
// $tag_name, assuming the contents are text

function get_tag_contents($xmlString, $tagName)
{

if (preg_match_all(get_tag_match_string($tagName), $xmlString, $matches))
{
return $matches[1][0];
}
else
{
return 0;
}
}

// get_tag_contents_array: returns the contents of the element
// $tag_name, assuming the contents are a list of elements

function get_tag_contents_array($xmlString, $tagName)
{

if (preg_match_all(get_tag_match_string($tagName), $xmlString, $matches))
{
return $matches[1];
}
else
{
return 0;
}
}

//isbn_and_branchNo_ok: veryfies existence of book in current store. true/false
function artikelnr_ok($artikelnr) {
global $connection;

$sql = "SELECT lager_artikel FROM Lagersaldo WHERE lager_artikel = '$artikelnr';";

$result = mysql_query( $sql, $connection ) OR DIE( mysql_error() );

if(!mysql_num_rows( $result ) ) {
return false;
} else {
return true;
}

}

//update_database: uppdaterar i databasen

function update_database($artikelnr, $antal) {
global $connection;

$query = "SELECT lager_antal FROM Lagersaldo WHERE lager_artikel = '$artikelnr';";
//echo $query . "<br>";
$qResult = mysql_query($query, $connection) OR DIE(mysql_error());
$row = mysql_fetch_object($qResult);
$sum= $row->lager_antal;
//echo $sum . "<br>";
$totalAntal = $sum - $antal;
echo $totalAntal . "<br>";

$sql = "UPDATE Lagersaldo SET lager_antal = '$totalAntal' WHERE lager_artikel = '$artikelnr';";
//echo $sql . "<br>";
$result = mysql_query($sql, $connection) OR DIE(mysql_error());
}

//funktion updateStock extraherar data från de olika XML-elementen, och
//anropar de funktioner som beskrivs ovan

// update_storage: updates the book shop stock, given a
// valid XML document, stored in $xml_string.
// The contents of the XML document are also displayed, for
// information purposes

function updateStock($xmlString)
{
$staffName = get_tag_contents($xmlString, "staffName");
print "<br>Namn: ".$staffName;

$date = get_tag_contents($xmlString, "date");
print "<br>Datum: ".$date;

$time = get_tag_contents($xmlString, "time");
print "<br>Tidpunkt: ".$time;

print "<br>";

$updateItemArray = get_tag_contents_array($xmlString, "updateItem");
$noItems = count($updateItemArray);
print "<br>Antal element i listan: $noItems\n";

for ($i = 0; $i < $noItems; $i++)
{
$artikelnr = get_tag_contents($updateItemArray[$i], "artikelnr");
print "<br>Artikelnummer[$i]: ".$artikelnr;

$antal = get_tag_contents($updateItemArray[$i], "antal");
print "<br>Antal[$i]: ";

// check if $isbn and $branchNo is a valid combination
if (artikelnr_ok($artikelnr))
{
update_database($artikelnr, $antal);
print "<br>Database update Ok!";
}
else
{
print "<br><strong>NOTE: $artikelnr and $antal is not a " .
"valid combination!!!</strong>";
}

print "<br>";
}
}

?>