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");
     }
 }
 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");
     }
 }