Dropdown selection -> second dropdown

[SysX]

Does anyone know of a way to execute an if (isset([])) function from a selection in a drpodown menu?

I have a dropdown menu that diaplays items from a database:

<?php
		//Create dropdown criteria for relationship sub-category
		$values = array ( );
		$labels = array ( );
		$query = "SELECT swcontti_id, descr FROM swcontti ORDER BY descr";
		$result = $conn->issue_query ($query);
		if ($result)
		{
			while (list ($swcontti_id, $descr) = mysql_fetch_row ($result))
			{
				$values[] = $swcontti_id;
				$labels[] = $descr;
			}
		}

		//Print SQL query results
		print (make_popup_menu ("swcontti", $values, $labels, ""));
?>

I would like to be able to show a second dropdown from the selection of one item from this dropdown (swcontti).

Can anyone help me please?

Kind regards,

SysX

[SysX]

The answer to this is you can't use anything in PHP that's like on select as it's serverside but you can do the obvious alternative:

Have a dropdown that if X is selected produce table X if
Y is selected produce Y, or create tabs instead...