Testfall

$mysqli = new mysqli("localhost", "root", "", "BookStore");

$bookStore = new BookStore($mysqli);

$controller = new AddBookController($bookStore);

echo $controller->addBook();

BookStore.php

/**
	* @var BookDAL
	*/ 
	private $bookDAL;

	public function __construct(mysqli $dbConnection) {
		$this->bookDAL = new BookDAL($dbConnection);

		$this->books = $this->bookDAL->getAllBooks();
	}
/**
	* @param Book book The book to be added
	* @return boolean Return true if book was added, 
	*                        false if book already was in store...
	*/
	public function addBook(Book $book) {
		if ($this->isBookInStore($book))
			return false;

		//Add book to the end of the array
		$this->books[] = $book;
		$this->bookDAL->insertBook($book);

		return true;
	}

BookDAL.php

<?php

require_once("Book.php");
/*
* Data Acess Layer (DAL) for Books
*/
class BookDAL {
	private static $tableName = "book";

	/**
	* @var mysqli 
	*/
	private $mysqli;

	/**
	* @param mysqli  http://www.php.net/manual/en/book.mysqli.php
	*/
	public function __construct(mysqli $mysqli) {
		$this->mysqli = $mysqli;
	}

	/**
	* @throws Exception on error
	*/
	public function createTable() {
      	$sql = "CREATE TABLE `" . self::$tableName . "` 
      		(
      			`pk` INT NOT NULL AUTO_INCREMENT PRIMARY KEY, 
      			`author` VARCHAR(255),
      			`title` VARCHAR(255),
      			`isbn` VARCHAR(255)
      		)
      		ENGINE = MyISAM;";
      
      if ($this->mysqli->query($sql) === FALSE) {
          throw new Exception("'$sql' failed " . $this->mysqli->error);
      }
    }

    /**
    * @param Book the book to insert
    * @throws Exception if something goes wrong.
    */
    public function insertBook(Book $book) {
		$sql = "INSERT INTO " . self::$tableName . " 
			(
				author, 
				title, 
				isbn
			) 
			VALUES(?, ?, ?)";

		//http://www.php.net/manual/en/mysqli-stmt.prepare.php
		$statement = $this->mysqli->prepare($sql);
		if ($statement === FALSE) {
			throw new Exception("prepare of $sql failed " . $this->mysqli->error);
		}

		//http://www.php.net/manual/en/mysqli-stmt.bind-param.php
		if ($statement->bind_param("sss", $book->author, 
										  $book->title, 
										  $book->isbn) === FALSE) {
			throw new Exception("bind_param of $sql failed " . $statement->error);
		}

		//http://www.php.net/manual/en/mysqli-stmt.execute.php
		if ($statement->execute() === FALSE) {
			throw new Exception("execute of $sql failed " . $statement->error);
		}

    }

	/**
    * @return array of Book objects
    */
    public function getAllBooks() {
    	$ret = array();

    	$sql = "SELECT 
    				author, 
					title, 
					isbn FROM " . self::$tableName . ";";

		//http://www.php.net/manual/en/mysqli-stmt.prepare.php
		$statement = $this->mysqli->prepare($sql);
		if ($statement === FALSE) {
			throw new Exception("prepare of $sql failed " . $this->mysqli->error);
		}

		//http://www.php.net/manual/en/mysqli-stmt.execute.php
		if ($statement->execute() === FALSE) {
			throw new Exception("execute of $sql failed " . $statement->error);
		}

		//http://www.php.net/manual/en/mysqli-stmt.get-result.php
		$result = $statement->get_result();
			
		//http://www.php.net/manual/en/mysqli-result.fetch-array.php
		while ($object = $result->fetch_array(MYSQLI_ASSOC))
        {
        	$ret[] = new Book($object["author"], 
        					  $object["title"], 
        					  $object["isbn"]);


           	
        }

        return $ret;
    }

}