My browser keeps refreshing - php

Question

After I created an if inside a SELECT tag (HTML) my browser keeps refreshing.
The purpose of this if is to make an OPTION selected when the condition appear.
I also have done this earlier on the same page and it worked.
My guess is that having the 2 SELECT dropdowns on the same page, having this code is making them to refresh each other (I have a jQuery to do onchange actions).
the code is this:
<select name="ddequipamento" id="ddequipamento" class="cliente" <? if (!$_GET['id']) echo "disabled" ?> >
<option value="---">---</option>
<?
if ($_GET['id'])
{
for ($i = 0; $i < $count_equipamento; $i++)
{
$idequipamento = mysql_result($result_equipamento,$i,"idequipamento");
$marca = mysql_result($result_equipamento,$i,"marca");
$tipo_equipamento = mysql_result($result_equipamento,$i,"tipo_equipamento.tipo_equipamento");
$num_serie = mysql_result($result_equipamento,$i,"num_serie");
echo (' <option value="'.$idequipamento .'" ');
if ($_GET['eq'] = $idequipamento){
echo (' selected="true" ');
}
echo (' >'.$tipo_equipamento. ' - '. $marca . ' - '. $num_serie .'</option>');
}
}
?>
<option value="0" >Novo</option>
</select>
and the jQuery:
$(document).ready(function () {
$('#ddcliente').change(function () {
window.location.href = "index.php?id="+ $(this).val();
});
});

Answer 1

Please pass "eq" through URL , Please change it in script,
$(document).ready(function () {
$('#ddcliente').change(function () {
window.location.href = "index.php?id="+ $(this).val()+"&eq=<?php echo $_GET['eq'];?>";
});
});
If you want to "id" only then change in PHP part,
if ($_GET['id'] = $idequipamento){ //OLD if ($_GET['eq'] = $idequipamento){
echo (' selected="true" ');
}
IF TWO DROPDOWNS WITH DIFFERENT ID "eq" and "id"
if you have 2 drop-downs use,
$(document).ready(function () {
$('#ddcliente').change(function () {
window.location.href = "index.php?id="+ $(this).val()+"&eq=<?php echo $_GET['eq'];?>";
});
$('#ddcliente2').change(function () { //CHANGE THE ID OF SECOND DROPDOWN
window.location.href = "index.php?eq="+ $(this).val()+"&id=<?php echo $_GET['id'];?>";
});
});
and also change the PHP part for 2 drop-downs
// FIRST DROP DOWN
if ($_GET['id'] = $idequipamento){ //OLD if ($_GET['id'] = $idequipamento){
echo (' selected="true" ');
}
// SECOND DROP DOWN , CHANGE VARIABLE NAME of $idequipamento2
if ($_GET['eg'] = $idequipamento2){ //OLD if ($_GET['eq'] = $idequipamento){
echo (' selected="true" ');
}