如果我向C＃中的现有行添加新行，如何更新datagridview？

Question

在我的程序中有datagridview用于插入，更新或删除Purchase Order，它的行为就像购物车一样。这个datagridview包含BookName，ISBNNo，订单数量，单价和总数。当我将这个datagridview数据插入数据库时，每行插入唯一ID为PO_Cart_No（pk）且具有标识值。

还有其他背景文本框详细信息，即Po_No，supplier_Id和Grand total details插入到单独的表中，称为PO表。此外，这两个表与外键PO_No链接。我的问题是当我向现有行添加新行时更新数据库，新行没有插入，其他行数据已更新。 问题出在哪里。这是我的代码，

public void UpdatePurchseOrderTable(int PO_No,int Supplier_ID, string Date, string RequiredDate, double GrandTotal)
    {
        DynamicConnection con = new DynamicConnection();
        con.mysqlconnection();
        string query = "UPDATE TBL_PO "
            + " SET Supplier_ID = @Supplier_ID,Date = @Date,"
            + "RequiredDate = @RequiredDate,GrandTotal=@GrandTotal"
             + " WHERE PO_No = @PO_No";
        con.sqlquery(query);
        con.cmd.Parameters.Add(new SqlParameter("@PO_No", SqlDbType.Int));
        con.cmd.Parameters["@PO_No"].Value = PO_No;
        con.cmd.Parameters.Add(new SqlParameter("@Supplier_ID", SqlDbType.Int));
        con.cmd.Parameters["@Supplier_ID"].Value = Supplier_ID;
        con.cmd.Parameters.Add(new SqlParameter("@Date", SqlDbType.Date));
        con.cmd.Parameters["@Date"].Value = Date;
        con.cmd.Parameters.Add(new SqlParameter("@RequiredDate", SqlDbType.Date));
        con.cmd.Parameters["@RequiredDate"].Value = RequiredDate;
        con.cmd.Parameters.Add(new SqlParameter("@GrandTotal", SqlDbType.Money));
        con.cmd.Parameters["@GrandTotal"].Value = GrandTotal;
        con.nonquery();
    }

    public void UpdatePOCartTable(int PO_No,string ISBN_No,int OrderQuantity, double UnitPrice, double Total)
    {
        DynamicConnection con = new DynamicConnection();
        con.mysqlconnection();
        string query = "UPDATE TBL_PO_Cart"
            + " SET ISBN_No = @ISBN_No, OrderQuantity= @OrderQuantity,"
            + "UnitPrice= @UnitPrice,Total=@Total"
            + " WHERE PO_No = @PO_No";
        con.sqlquery(query);
        con.cmd.Parameters.Add(new SqlParameter("@PO_No", SqlDbType.Int));
        con.cmd.Parameters["@PO_No"].Value = PO_No;
        con.cmd.Parameters.Add(new SqlParameter("@ISBN_No", SqlDbType.NVarChar));
        con.cmd.Parameters["@ISBN_No"].Value = ISBN_No;
        con.cmd.Parameters.Add(new SqlParameter("@OrderQuantity", SqlDbType.NVarChar));
        con.cmd.Parameters["@OrderQuantity"].Value = OrderQuantity;
        con.cmd.Parameters.Add(new SqlParameter("@UnitPrice", SqlDbType.Money));
        con.cmd.Parameters["@UnitPrice"].Value = Math.Round(UnitPrice,2,MidpointRounding.AwayFromZero);
        con.cmd.Parameters.Add(new SqlParameter("@Total", SqlDbType.Money));
        con.cmd.Parameters["@Total"].Value = Math.Round(Total,2,MidpointRounding.AwayFromZero);
        con.nonquery();
    }

和PO表格数据如下

 private void btnedit_Click(object sender, EventArgs e)
    {
        DynamicConnection con = new DynamicConnection();
        try
        {
            if (txtPONo.Text != "" || cmbsupID.Text != "" || date1.Text != "" || requireddate.Text != "" || txtgrandTotal.Text != "")
            {
                PurchaseOrder PO = new PurchaseOrder();
                if (cmbsupID.Text.Contains('-'))
                {
                    string str = cmbsupID.Text;
                    int index = str.IndexOf('-');
                    if (index > 0)
                    {
                        int value = int.Parse(str.Substring(0, index));
                        PO.UpdatePurchseOrderTable(Convert.ToInt32(txtPONo.Text), value, date1.Text, requireddate.Text, Convert.ToDouble(txtgrandTotal.Text));
                    }
                }
                else
                {
                    int value2 = Convert.ToInt32(cmbsupID.Text);
                    PO.UpdatePurchseOrderTable(Convert.ToInt32(txtPONo.Text), value2, date1.Text, requireddate.Text, Convert.ToDouble(txtgrandTotal.Text));
                }

                for (int i = 0; i < dataGridView1.Rows.Count-1; i++)
                {
                    int PONO = Convert.ToInt32(txtPONo.Text);
                    string column1 = Convert.ToString(dataGridView1.Rows[i].Cells[1].Value);
                    int column2 = Convert.ToInt32(dataGridView1.Rows[i].Cells[2].Value);
                    double column3= Convert.ToDouble(dataGridView1.Rows[i].Cells[3].Value);
                    double column4 = Convert.ToDouble(dataGridView1.Rows[i].Cells[4].Value);
                    PO.UpdatePOCartTable(PONO,column1,column2,column3,column4);

                }
            }
            else
            {
                MessageBox.Show("Please Provide Details!");
            }
            dataGridView1.Rows.Clear();
            ClearData();
            retviewPO_No();
            MessageBox.Show("Record Updated Successfully");
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
        }
    }