The Script

#!/usr/bin/perl -wT
use strict;

use XML::LibXML;
use XML::LibXSLT;

# Create XML Document
my $dom = XML::LibXML::Document->createDocument('1.0');
my $root = $dom->createElement('categories');
$dom->setDocumentElement($root);

#create cat element at append it to root
for (<DATA>) {
        chomp;
        my ($id,$name,$parent) = split(/\,/,$_);
        my $elem = $dom->createElement('cat');
        $elem->setAttribute('catid',$id);
        $elem->setAttribute('name',$name);
        $elem->setAttribute('parent',$parent);
        $root->appendChild($elem);
}

# Load and apply XSLT stylesheet
my $xslt = XML::LibXSLT->new();
my $stylesheet = $xslt->parse_stylesheet_file('catnames.xsl');
my $results = $stylesheet->transform($dom);
print $results->toString(1);

__DATA__
26,PWC,0
24,Truck,0
22,Snowmobile,0
30,Parts,22
31,Accessories,22
32,Off Road Bikes,0
33,Road Bikes,0
34,HJC,31
40,Reeds,26
41,Intake Grates,26
44,Accessories,24
98,Demo,40
99,Pop,98
[download]

The XSLT file:

<?xml version="1.0"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" versi
+on="1.0">
  <xsl:output method="xml" version="1.0"/>
  <xsl:template match="/">
    <catnames>
    <xsl:apply-templates select="//categories/cat[@parent = 0]"/>
    </catnames>
  </xsl:template>
  <xsl:template match="cat">
    <cat>
    <xsl:attribute name="catid">
      <xsl:value-of select="@catid"/>
    </xsl:attribute>
    <xsl:param name="parent-name"/>
    <xsl:if test="$parent-name">
      <xsl:value-of select="$parent-name"/>
      <xsl:text>-></xsl:text>
    </xsl:if>
    <xsl:value-of select="@name"/>
    </cat>
    <xsl:apply-templates select="//categories/cat[@parent = current()/
+@catid]">
      <xsl:with-param name="parent-name">
        <xsl:if test="$parent-name">
          <xsl:value-of select="$parent-name"/>
          <xsl:text>-></xsl:text>
        </xsl:if>
        <xsl:value-of select="@name"/>
      </xsl:with-param>
    </xsl:apply-templates>
  </xsl:template>
</xsl:stylesheet>
[download]

The Output:

<?xml version="1.0"?>
<catnames>
  <cat catid="26">PWC</cat>
  <cat catid="40">PWC-&gt;Reeds</cat>
  <cat catid="98">PWC-&gt;Reeds-&gt;Demo</cat>
  <cat catid="99">PWC-&gt;Reeds-&gt;Demo-&gt;Pop</cat>
  <cat catid="41">PWC-&gt;Intake Grates</cat>
  <cat catid="24">Truck</cat>
  <cat catid="44">Truck-&gt;Accessories</cat>
  <cat catid="22">Snowmobile</cat>
  <cat catid="30">Snowmobile-&gt;Parts</cat>
  <cat catid="31">Snowmobile-&gt;Accessories</cat>
  <cat catid="34">Snowmobile-&gt;Accessories-&gt;HJC</cat>
  <cat catid="32">Off Road Bikes</cat>
  <cat catid="33">Road Bikes</cat>
</catnames>
[download]

I leave it as an exercise for the reader to pull the data from MySQL rather than the __DATA__ chunk. Once the new XML document is stored in $results, you could either use it as is, with a simple XPath function to lookup the category name by ID, or you could extract the category names and IDs and stick them in a hash.

-rattus, playing with his current favorite tool

__________
He seemed like such a nice guy to his neighbors / Kept to himself and never bothered them with favors
- Jefferson Airplane, "Assassin"