public static ArrayList<Book> getAllRentedBooks() {
		
		try {
			   if(conn == null || conn.isClosed()){
			    conn = DatabaseConnection.getConnection();
			   }
			  } catch (SQLException e1) {
			   // TODO Auto-generated catch block
			   e1.printStackTrace();
			  }
		
		ArrayList<Book> bookList = new ArrayList<Book>();
		Book b = null;
		try {
			Statement stmnt = conn.createStatement();
			String sql = "SELECT * FROM Books b WHERE b.book_id = (SELECT book_id FROM BookCopies bc, Rentals r WHERE bc.book_id = b.book_id AND bc.copy_id = r.product_id AND r.type = 'boek' AND r.rental_id = (SELECT rental_id FROM RentTransactions rt WHERE rt.rent_trans_id = r.rental_id AND rt.closed = 0))";
			
			ResultSet res = stmnt.executeQuery(sql);
			while(res.next()) {
				b = new Book(res.getDate("year"), res.getString("place_of_publication"),
						res.getString("title"), res.getString("genre"), res.getString("author"),
						res.getString("isbn"), res.getString("publisher"), res.getInt("book_id"));
				bookList.add(b);
			}

		}
		catch(SQLException e) {
			System.out.println(e);
		}
		
		return bookList;
	}