I am trying to duplicate on my page these three linked drop down menus.
Tried to copy and paste the code, but it doesn't work. They will all stop working. Can you help me understand how to do it?
Code:
<?php

require "config.php";
?>

<!doctype html public "-//w3c//dtd html 3.2//en">

<html>

<head>
<title>Demo of Three Multiple drop down list box from plus2net</title>

<SCRIPT language=JavaScript>
function reload(form)
{
var val=form.cat.options[form.cat.options.selectedIndex].value; 
self.location='duplicate.php?cat=' + val ;
}
function reload3(form)
{
var val=form.cat.options[form.cat.options.selectedIndex].value; 
var val2=form.subcat.options[form.subcat.options.selectedIndex].value; 

self.location='duplicate.php?cat=' + val + '&cat3=' + val2 ;
}

</script>
</head>
<body>
		<?

///////// Getting the data from Mysql table for first list box//////////
$quer2=mysql_query("SELECT DISTINCT category,cat_id FROM category order by category"); 
///////////// End of query for first list box////////////

/////// for second drop down list we will check if category is selected else we will display all the subcategory///// 
$cat=$HTTP_GET_VARS['cat']; // This line is added to take care if your global variable is off
if(isset($cat) and strlen($cat) > 0){
$quer=mysql_query("SELECT DISTINCT subcategory,subcat_id FROM subcategory where cat_id=$cat order by subcategory"); 
}else{$quer=mysql_query("SELECT DISTINCT subcategory,subcat_id FROM subcategory order by subcategory"); } 
////////// end of query for second subcategory drop down list box ///////////////////////////

/////// for Third drop down list we will check if sub category is selected else we will display all the subcategory3///// 
$cat3=$HTTP_GET_VARS['cat3']; // This line is added to take care if your global variable is off
if(isset($cat3) and strlen($cat3) > 0){
$quer3=mysql_query("SELECT DISTINCT subcat2 FROM subcategory2 where subcat_id=$cat3 order by subcat2"); 
}else{$quer3=mysql_query("SELECT DISTINCT subcat2 FROM subcategory2 order by subcat2"); } 
////////// end of query for third subcategory drop down list box ///////////////////////////

echo "<form method=post name=f1 action='confirm.php'>";

//////////        Starting of first drop downlist /////////
echo "<select name='cat' onchange=\"reload(this.form)\"><option value=''>Select one</option>";
while($noticia2 = mysql_fetch_array($quer2)) { 
if($noticia2['cat_id']==@$cat){echo "<option selected value='$noticia2[cat_id]'>$noticia2[category]</option>"."<BR>";}
else{echo  "<option value='$noticia2[cat_id]'>$noticia2[category]</option>";}
}
echo "</select>";
//////////////////  This will end the first drop down list ///////////

//////////        Starting of second drop downlist /////////
echo "<select name='subcat' onchange=\"reload3(this.form)\"><option value=''>Select one</option>";
while($noticia = mysql_fetch_array($quer)) { 
if($noticia['subcat_id']==@$cat3){echo "<option selected value='$noticia[subcat_id]'>$noticia[subcategory]</option>"."<BR>";}
else{echo  "<option value='$noticia[subcat_id]'>$noticia[subcategory]</option>";}
}
echo "</select>";
//////////////////  This will end the second drop down list ///////////


//////////        Starting of third drop downlist /////////
echo "<select name='subcat3' ><option value=''>Select one</option>";
while($noticia = mysql_fetch_array($quer3)) { 
echo  "<option value='$noticia[subcat2]'>$noticia[subcat2]</option>";
}
echo "</select>";
//////////////////  This will end the third drop down list ///////////

?>

</body>
</html>