[Dave]

It depends on where you place your script.
If your script is in the root and your forum is located in /forum/ then you can connect doing something like:

PHP Code:

require("forum/includes/config.php");
$dbname = "somedatabasename";

try {
    $db = new PDO("mysql:dbname=" . $dbname . ";host=" . $config['MasterServer']['servername'] . ";port=" . $config['MasterServer']['port'], $config['MasterServer']['username'], $config['MasterServer']['password']);
    $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
} catch(PDOException $e) {
    die('Could not connect to the database:<br/>' . $e);
}

$stmt = $db->prepare("SELECT mycolumn FROM sometable WHERE somevalue = ? AND somevalue2 = ?");
$stmt->execute(array("somevalue1", "somevalue2"));

// Iterate through data
foreach($stmt as $row){
   var_dump($row); // $row['mycolumn']
}

// Or if only one row result
$row = $stmt->fetch();
var_dump($row); // $row['mycolumn'] 


* Quickly wrote it without testing.