Dual dropdown + PHP/mysql

Update, jeg er kommet frem til foelgende fungerer paa en side for sig selv, men naar jeg indsaetter det i en formular sammen med andre felter, hvor et af dem bla. er et upload felt saa kan kan jeg ikke faa vaerdien/$_get til blive tildelt..

<?
@$cat=$_GET['cat']; // register_globals off

///////// Getting the data from Mysql table for first list box//////////
$quer2=mysql_query("SELECT Distinct maingenre FROM musicgenre order by maingenre");
///////////// 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/////
if(isset($cat)){
$quer=mysql_query("SELECT DISTINCT subgenre FROM musicgenre WHERE maingenre='$cat' order by subgenre");
}else{$quer=mysql_query("SELECT DISTINCT subgenre FROM musicgenre  order by subgenre"); }
////////// end of query for second subcategory drop down list box ///////////////////////////


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

//////////        Starting of second drop downlist /////////
echo "<select name='sugenre'><option value=''>Select one</option>";
while($noticia = mysql_fetch_array($quer)) {
echo  "<option value='$noticia[subgenre]'>$noticia[subgenre]</option>";
}
echo "</select>";
//////////////////  This will end the second drop down list ///////////
?>

Naar man aendrer i det foerste inputfelt saa burde der blive sat en variabel i adresselinjen der hedder cat. Kan det have nogen effekt at formularen i forvejen bliver automatisk genereret saa addresselinjen allerede hedder

createQuestions.php?id=22&questionnumber=1

naar man saa aender i forste dropdown, saa burde adressen blive
createQuestions.php?id=22&questionnumber=1&cat=Foo