private void btn_loan_Click(object sender, EventArgs e)   //Button loan book
        {
            int    i                = grid_results_adm.CurrentRow.Index;
            string isbn             = grid_results_adm["Isbn", i].Value.ToString();
            int    copy             = (int)grid_results_adm["CopyNbr", i].Value;
            BibliotechController bc = new BibliotechController();

            bc.LoanBook(isbn, copy, us.UserId);
            FillViewBooks();
        }
        private void btn_userloan_Click(object sender, EventArgs e)
        {
            int    i                = grid_results.CurrentRow.Index;
            string isbn             = grid_results["Isbn", i].Value.ToString();
            int    copy             = (int)grid_results["CopyNbr", i].Value;
            BibliotechController bc = new BibliotechController();
            BibliotechDAL        bd = new BibliotechDAL();
            int s = bd.CheckAvailability(isbn, copy);

            if (s == 1)
            {
                MessageBox.Show("Boken är utlånad");
            }
            else
            {
                bc.LoanBook(isbn, copy, us.UserId);
                ShowLoans();
            }
        }