Can I use a wpdb object to connect to a non-WordPress Oracle database [duplicate]

Question

This should be possible. You can try

    function seconddb() {
         global $seconddb;
         $seconddb = new wpdb('Username','password','database name','localhost')
     }
     add_action('init','seconddb');

in your functions.php.
Then you can fire a query to the new db like
$seconddb->get_row( "SELECT * FROM yourtable..." ); instead of $wpdb->get_row().