private String indexToString(int i){
		switch (i){
		case 0: return "Book";
		case 1: return "BookCopy";
		case 2: return "Borrower";
		case 3: return "BorrowerType";
		case 4: return "Borrowing";
		case 5: return "Fine";
		case 6: return "HasAuthor";
		case 7: return "HasSubject";
		case 8: return "HoldRequest";
		default: return null;
		}
	}