从数据库中获取自动增量值到文本框并复制键C＃Windows窗体

Question

我想在点击按钮后得到最新的ID，它的BillForm买东西所以我需要比尔ID作为Autoincrement。我有2个表，一个带有身份证，另一个不带BillDetails

我有这个查询来获取最新的账单，并在第一个Bill添加的Form Load中正常工作

 command.CommandText = "select top 1 (purchase_id)+1 from Purchase_bill order by purchase_id desc";

这个代码用于插入新帐单的按钮

        private void btn_save_Click(object sender, EventArgs e)
        {
            try
            {
                insert.insert_Purchase_bill(Convert.ToDecimal(txt_total.Text),
                Convert.ToDateTime(dateTimeBills.Text)
             , 1, Convert.ToDecimal(txt_discount.Text),
                Convert.ToInt32( combo_supplier.SelectedValue),
                Convert.ToInt32(combo_stockroom.SelectedValue));

                for (int i = 0; i < data_cashier.Rows.Count; ++i)
                {
                    insert.insert_Purchase_details(Convert.ToInt32(txt_billNumber.Text),
                        Convert.ToInt32(data_cashier.Rows[i].Cells["item_id"].Value),
                        Convert.ToInt32(data_cashier.Rows[i].Cells["Quantity"].Value),
                       Convert.ToDecimal(data_cashier.Rows[i].Cells["Price"].Value), 
                       Convert.ToInt32(data_cashier.Rows[i].Cells["depart_id"].Value)).ToString();
                }
                MessageBox.Show("تم اضافة الفاتورة بنجاح", "اضافة", MessageBoxButtons.OK, MessageBoxIcon.Information);
                resetbill(); //this func to clear the form
            }
            catch (Exception)
            {
                MessageBox.Show("لم يتم اضافة الفاتورة", "فشل", MessageBoxButtons.OK, MessageBoxIcon.Error);

            }
            finally
            {
                insert.execute_query(); // this from my INSERT class to close con
            }
            txt_billNumber.Text = Convert.ToString(select.getLatestPurchaseBill()); //this the same code line which in FormLoad
        }

这实际上工作正常但添加新帐单后清除此错误出现

违反主键约束无法插入重复键

Answer 1

这个代码没有错，因为连接问题总是打开并需要强制关闭“con.close”使用try和catch in the func

        public int getLatestBill()
    {
        DataTable dt = new DataTable();
        try
        {
            command.CommandType = CommandType.Text;
            command.CommandText = "getLatestBill";

            SqlDataAdapter adapt = new SqlDataAdapter(command);
            connect.Open();
            adapt.Fill(dt);
        }
        catch (Exception)
        {
            throw;
        }
        finally
        {
            connect.Close();
        }

        return Convert.ToInt32(dt.Rows[0][0]);
    }