function replaceBook(Book $newBook)
{
    $db = new ServerDatabase();
    $db->newQuery("UPDATE book SET author='%2', title='%3', image='%4', category=%5 WHERE id=%1");
    $db->addParameter($newBook->id);
    $db->addParameter($newBook->author);
    $db->addParameter($newBook->title);
    $db->addParameter($newBook->image);
    $db->addParameter($newBook->category);
    $db->execute();
    return $db->getRowsAffected() > 0;
}