private void add_issue_bt_Click(object sender, EventArgs e) { if (Convert.ToInt16(grid_books.CurrentRow.Cells["available"].Value) > 0) { add_issue_fm add_issue_fm = new add_issue_fm(conn, Convert.ToInt16(grid_books.CurrentRow.Cells["id"].Value), Convert.ToInt16(grid_books.CurrentRow.Cells["available"].Value)); add_issue_fm.add_rent_book_author.Text = grid_books.CurrentRow.Cells["author"].Value.ToString(); add_issue_fm.add_rent_book_name.Text = grid_books.CurrentRow.Cells["name"].Value.ToString(); add_issue_fm.Show(); add_issue_fm.FormClosed += add_form_closed; } else { MessageBox.Show("Количество книг равно нулю", "Невозможно выдать книгу"); } }