protected void borrowButton_Click(object sender, EventArgs e)
        {
            string     number      = memberNoTextBox.Text;
            MemberBll  aMemberBll  = new MemberBll();
            BookEnroll aBookEnroll = new BookEnroll();
            BookBLL    aBookBll    = new BookBLL();

            if (aMemberBll.CheckMemberExistance(number) == true)
            {
                messageLable.Text = "";
                BorrowBookBll aBorrowBookBll = new BorrowBookBll();

                aBookEnroll.BookID       = (int)ViewState["bookId"];
                aBookEnroll.MemberNumber = number;
                if (aBookBll.CheckBookDuplication(aBookEnroll) == true)
                {
                    messageLabel.Text = "This book already you take";
                }
                else
                {
                    messageLabel.Text = "";
                    aBorrowBookBll.Save(aBookEnroll);
                }
            }
            else
            {
                messageLable.Text = "This Member Number doesn't exist";
            }
        }
        protected void returnButton_Click(object sender, EventArgs e)
        {
            BookEnroll    aBookEnroll    = new BookEnroll();
            BorrowBookBll aBorrowBookBll = new BorrowBookBll();

            aBookEnroll.MemberNumber = memberNumberTextBox.Text;
            int  index = bookListDropDownList.SelectedIndex;
            Book aBook = aBorrowBookEnroll.TakenBooks(aBookEnroll.MemberNumber)[index];

            aBookEnroll.BookID = aBook.Id;
            aBorrowBookBll.ReturnBook(aBookEnroll);
        }