I wanted to incorporate a PHP/SQL search against a non-WP Database into WordPress page. After struggling with a few plug-ins and "new wpdb" code I got creative. I simply added an iframe to the HTML tab. Everything execute outside of WP and therefore creates the same results as the previous application, DB code unchanged and it even uses the CSS form the app.
<IFRAME src="../new/search.php" width="100%" height="400px" frameborder=0 marginheight=0 marginwidth=0><p>Your browser does not support iframes.</p> </IFRAME>