mysql> SELECT Auto_Increment FROM information_schema.tables WHERE table_name='charlist';

+----------------+
| Auto_Increment |
+----------------+
|              7 |
+----------------+

// Configuration.
    $username = "root";
    $password = "root";
    $hostname = "localhost";
    $dbname = "asoiaf";
    $tablename = "charlist";

    // Opens a connection to the database.
    try {
        $conn = new PDO("mysql:host=$hostname;dbname=$dbname", $username, $password);
        $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    } catch(PDOException $e) {
        echo $e->getmessage();
    }

    // Gets all the information from POST.
    $autoidquery = "SELECT Auto_Increment FROM information_schema.tables WHERE table_name='$tablename'";
    $id = $conn->query("SELECT Auto_Increment FROM information_schema.tables WHERE table_name='$tablename'");
    // This should output the auto-incremented primary key, but nothing is output.
    echo $id."<br>Hello world";