// Lets check if id is an integer.
if(ctype_digit($_GET['id'])) {
// Yes, it is, so we set $id.
	$id = $_GET['id'];
}
elseif(is_numeric($_GET['id'])) {
	$title = "Error";
	$description = "Sorry, no id was specified.";
	include("error.php");
	}
// Lets check if the id exists in the database.	
$q = mysql_query("select id from casinos where id = '$id'") or die(mysql_error());
elseif(mysql_num_rows($q) == 0) {
// No it isn't, so we output an error.
	echo '<h2>Error</h2>
				<p><a href="/all.php">View  All Casino\'s</a></p>
			</div>';
	$title = "Error";
	$description = "Sorry, that id was not found in our database.";
	include("error.php");
	}