You can't really obfuscate the source of an iframe, as the browser needs to be able to read it.
However, you could use cURL to open pages.
So, for example:
//in your iframe page
<iframe src="curl.php?id=1"></iframe>
//and then in curl.php
$id = $_GET['id'];
$sql = mysql_query("SELECT * FROM table WHERE ID='$id'");
$fetch = $mysql_fetch_array($sql);
$link = $fetch['link'];
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $link);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
$return = curl_exec($ch);
curl_close($ch);
echo $return;
Something like that anyway.