Select database table depending on select box value (php + Ajax) - php

Question

Okay this is driving me crazy now, I can't seem to find a solution at all!
Basically I have two select boxes on my page, However I want the second select box to to be populated from a mysql database depending on the value of the first select box.
For example if I choose the value 'misc' from the first select box, the second select would be populated with the misc table from my database! (the second select box will be refreshed via ajax on first select box choice change)
My only problem is I can't think of a way to store the value of the first select box in a php variable, so it can be used in my function to populate the second select box(which is refreshed by ajax)
Thanks guys
<form action="scripts/tp/process.php" method="post" enctype="multipart/form-data">
Select teleport here:
<select name="selectmate" id="Testid" onchange='Ajax();'>
<option value="Misc">Misc...</option>
<option value="Stunt">Stunt</option>
<option value="deathmatches">Deathmatches</option>
<option value="Car"> Car </option>
<option value="Races">Races </option>
</select>
<br/>
<label for="file">Filename:</label>
<input name="file" type="file"/>
<br/>
<label for="Name">Teleport name:</label>
<input type="text" name="Name" id="Name"/>
<br/>
<label for="Tp"> Teleport command:</label>
<input type="text" name="Tp" id="Tp"/>
<br/>
<label for="Info">teleport infomation</label>
<input type="text" name="Info" id="Info"/>
<br/>
<input type="submit" name="submit" value="Submit"/>
</form>
<h2>Delere entry here!</h2>
<form action="scripts/misc/miscdelete.php" method="post" enctype="multipart/form-data">
<select name="deletemisc">
<?php
ListDatabase($value);
?>
</select>
<input type="submit" name="delete" value="Delete"/>
</form>
I need to store the value of the first select box in the variable $value

Answer 1

$("#Testid").change(function () {
var val = $("#Testid option:selected").text();
// here your ajax request
// Fill second select here:
var deletemisc = $("#deletemisc");
$("#deletemisc > option").remove();
$.post("/path/to/script", { selected_val: val}, function(result) {
$.each(result, function (item) {
deletemist.append($("<option />").val(item.val).text(item.text));
})
});
});​
"/path/to/script" - must return json array of vals.