private void checkBorrow_Click(object sender, EventArgs e)
        {
            if (idUsertb.Text == "")
            {
                MessageBox.Show("Enter Correct User ID!");
            }

            else
            {
                String id = idUsertb.Text;

                borrowstb.Text = "";
                BookReturner br = new BookReturner();
                br.checkBorrowedBook(id, borrowstb);
            }
        }
        private void returnOk_Click(object sender, EventArgs e)
        {
            if (uid.Text == "" || bid.Text == "")
            {
                MessageBox.Show("Enter Correct User ID and Book Number!");
            }
            else
            {
                String id     = uid.Text;
                String idbook = bid.Text;

                BookReturner br = new BookReturner();
                br.returnAccept(id, idbook, tbRetrn);

                borrowstb.Text = "";
            }
        }
        private void returnOk_Click(object sender, EventArgs e)
        {
            if (uid.Text == "" || bid.Text == "") { MessageBox.Show("Enter Correct User ID and Book Number!"); }
            else
            {
                String id = uid.Text;
                String idbook = bid.Text;

                BookReturner br = new BookReturner();
                br.returnAccept(id, idbook,tbRetrn);

                borrowstb.Text = "";
            }
        }
        private void checkBorrow_Click(object sender, EventArgs e)
        {
            if (idUsertb.Text == "") { MessageBox.Show("Enter Correct User ID!"); }

            else
            {
                String id = idUsertb.Text;

                borrowstb.Text = "";
                BookReturner br = new BookReturner();
                br.checkBorrowedBook(id, borrowstb);
            }
        }