搜索时单元格值返回其原始值

Question

您好GoodMorning我实际上遇到了datagridview

的问题

- 借书后，价值将变为0

- 问题是，当我再次开始搜索那本书时，它显示的值为1，这将允许我再次借用那本书

• 这是我的复习代码

          connection.Open();
          OleDbCommand command = new OleDbCommand();
          command.Connection = connection;
          string query = "select *from Books";
          command.CommandText = query;
  
          OleDbDataAdapter da = new OleDbDataAdapter(command);
          DataTable dt = new DataTable();
          da.Fill(dt);
          dataview6.DataSource = dt;
          connection.Close();
  

这是我借书的代码

private void borrow()
    {
        try
        {
            connection.Open();
            OleDbCommand cmd = new OleDbCommand();
            cmd.Connection = connection;
            cmd.CommandText = "UPDATE Books Set Copies = Copies -1 WHERE BOOK_NUMBER = " + bkn_num.Text + "";
            cmd.ExecuteNonQuery();
            MessageBox.Show("Book Has Been Borrowed");
            connection.Close();
        }
        catch (Exception ex)
        {

        }

    }