You are correct, if you just add the else to the end, which will be your default image:
}else {
$image = "default.jpg";
}
and change your first line to say:
$CategoryID = (isset($_GET['CategoryID']))?$_GET['CategoryID']:"";
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.