MySQL joins and two drop down boxes

[ReekaJean]

Alright... first of all - I have searched... and none of the answers really explain anything that does me any good....

So I'm posting this in the newbies forum, because well - I'm far from being experienced with php... and I don't know any javascript minus copy and pasting. lol.

I'm creating an upload form for myself so that I can easily add my graphics into cateogories... some of the categories have sub-categories... but not all of them do.

So, what I'm wanting to do is have 1 drop down box for the cats... if the cat I select has a subcat, I want the second drop down to be populated with the subcats for that category.

I've got two mysql tables - icon_categories and icon_subcats. I can get the categories dropdown to populate, but then how would I go about getting the second one to populate only where the cat_id from icon_categories (the first box) = the cat_id from icon_subcats.... ?

I know how to preform the join and all of that... I just can't seem to figure out what I need to do to get which category was selected in order to populate the second box....

and if there is any way I can do this without integrating javascript, I would be most appreciative....

But I really need somewhat of a thorough explination, as I'm trying to understand how it all works at the same time.

Thanks again,
-Erica

[ReekaJean]

Okay... I've been messing around trying to figure this out...

This is my code:

<?php

$imgdir = "../icons";
$title = "Upload Icons";
$contenttitle = "Upload LJ Icons";
include "header.php";

//Start the Page
$upload_fields = '';
$counter = 1;

//More Fields?
$field_number = (isset($_GET['n']))?
	(int)($_GET['n']) : 10;

?>

<script language="JavaScript">
		function resubmit()
		{
			document.myform.dothis="addicons.php";
			document.myform.submit();
		}
		function process()
		{
			document.myform.dothis="uploadicons.php";
			document.myform.submit();
	}
</script>

<h3>Upload Images</h3>
<?php
				print ("<form name=\"myform\" method=\"post\" action=\"uploadicons.php\" />");
				print ("<input type=\"hidden\" name=\"dothis\" value=\"addicons\" />");
		while ($counter <= $field_number) {
					print ("<select name=\"cat\" onchange=\"resubmit()\">");
					print("<option value=\"\">Categories</option>");
						require "database.php";
						$query = "SELECT * FROM icon_categories ORDER BY cat_name DESC";
						$result = mysql_query($query);
							while($row = mysql_fetch_array($result, MYSQL_NUM)) {
							$cat = $_GET['cat'];
								if($row[0] == $cat) {
										print("<option selected value=\"$row[0]\">$row[1]</option>");
								} else {
										print("<option value=\"$row[0]\">$row[1]</option>");
								}
							}
					print ("</select>");

				print ("<select name=\"subcat\">");
				print ("<option value=\"\">Sub Categories</option>");

				$cat = $_GET['cat'];
				if (isset($cat)) {
						$query2 = "SELECT * FROM icon_subcats WHERE cat_id = $cat ORDER BY sub_name DESC";
						$result2 = mysql_query($query2);
				} else {
						$query2 = "SELECT * from icon_subcats ORDER BY sub_name DESC";
						$result2 = mysql_query($query2);
				}
						while ($row2 = mysql_fetch_array($query2, MYSQL_NUM)) {
								print ("<option value=\"$row2[0]\">$row2[1]</option>");
						}

				print ("</select>");

				print ("<b>File</b>: <input type=\"file\" name=\"filename\" />");
				print ("<b>Caption</b>: <input type=\"text\" name=\"caption\" />");
			$counter++;
	}
?>
<input type="submit" name="submit" value="Add Icons" />
</form>

In Firefox - nothing happens. The page doesn't reload when I select a category from the first box.

In IE I get this error when I select a category "Object doesn't support this property or method" in this line:

		document.myform.dothis="addicons.php";

So... I'm not really sure where to go from here.