asp.net ระบบตระกร้าสินค้า รบกวนช่วยดูการบันทึกค่าที่แสดงใน GridView ให้ทีครับผม

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.Data.SqlClient;
using System.Text;



public partial class Viewcart : System.Web.UI.Page
{
    protected double strTotal = 0;
    protected double strSumTotal = 0;

    protected void Page_Load(object sender, EventArgs e)
    {
        df();
        BindGird();
        this.lblSumTotal.Text = strSumTotal.ToString("#,###.00");
    }
    protected void connect_db()
    {
        try
        {
            dbcon.connecToDB();
            Response.Write("เชื่อมต่อฐานข้อมูลสำเร็จ<br />");
        }
        catch (Exception ex)
        {
            Response.Write("เชื่อมต่อฐานข้อมุลไม่สำเร็จ <br />" + ex);
        }
    }
    protected void df()
    {
        if (Session["cususer"] == null)
        {
            Response.Redirect("Login.aspx");
        }
    }
    protected void BindGird()
    {
        DataTable dt = (DataTable)Session["myCart"];
        this.GridView1.DataSource = dt;
        this.GridView1.DataBind();
    }
    
   
     
    protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)
    {
        if (e.CommandName == "Del")
        {
            int RowsID = Convert.ToInt32(e.CommandArgument);
            DataTable dt = null;

            dt = (DataTable)Session["myCart"];

            dt.Rows[RowsID].Delete();

            Session["myCart"] = dt;

            Response.Redirect("ViewCart.aspx");

        }
    }
    protected DataTable getProductDet(string strProductID)
    {
       

           connect_db();
           SqlCommand cmd = new SqlCommand("select * from [Product] WHERE Pro_ID = " + strProductID + " ", dbcon.conn);
           SqlDataReader read = cmd.ExecuteReader();
           DataTable dt = new DataTable();
           dt.Load(read);
           dbcon.closeDB();
           return dt;

    }
    protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
    {
        if (e.Row.RowType == DataControlRowType.DataRow)
        {
            //*** ProductID ***//
            Label lblProductID = (Label)e.Row.FindControl("lblProductID");
            if ((lblProductID != null))
            {
                lblProductID.Text = DataBinder.Eval(e.Row.DataItem, "Pro_ID").ToString();
            }

            DataTable dt = getProductDet(DataBinder.Eval(e.Row.DataItem, "Pro_ID").ToString());

            //*** ProductName ***//
            Label lblProductName = (Label)e.Row.FindControl("lblProductName");
            if ((lblProductName != null))
            {
                lblProductName.Text = dt.Rows[0]["Pro_Name"].ToString();
            }

            //*** Price ***//
            Label lblPrice = (Label)e.Row.FindControl("lblPrice");
            if ((lblPrice != null))
            {
                lblPrice.Text = dt.Rows[0]["Pro_PricePerUnit"].ToString();
            }

            //*** Qty ***//
            Label lblQty = (Label)e.Row.FindControl("lblQty");
            if ((lblQty != null))
            {
                lblQty.Text = DataBinder.Eval(e.Row.DataItem, "ODt_Amount").ToString();
            }

            //*** Total ***//
            Label lblTotal = (Label)e.Row.FindControl("lblTotal");
            if ((lblTotal != null))
            {
                strTotal = Convert.ToDouble(DataBinder.Eval(e.Row.DataItem, "ODt_Amount")) * Convert.ToDouble(dt.Rows[0]["Pro_PricePerUnit"]);
                strSumTotal = Convert.ToDouble(strSumTotal) + strTotal;
                lblTotal.Text = strTotal.ToString("#,###.00");
            }

            //*** Delete ***//
            LinkButton lnkDelete = (LinkButton)e.Row.FindControl("lnkDelete");
            if ((lnkDelete != null))
            {
                lnkDelete.Text = "Delete";
                lnkDelete.CommandName = "Del";
                lnkDelete.CommandArgument = e.Row.RowIndex.ToString();
                lnkDelete.Attributes.Add("OnClick", "return confirm('Delete this row?');");
            }

        }
    }
    protected void lnkClearCart_Click(object sender, EventArgs e)
    {

        Session.Remove("myCart");
        Response.Redirect("Viewcart.aspx");
    }
    protected void lnkCheckOut_Click(object sender, EventArgs e)
    {
        DataTable dt = (DataTable)Session["myCart"];

        if (Session["myCart"] != null)
        {
            if (dt.Rows.Count > 0)
            {
                this.pnlCheckOut.Visible = true;
            }
        }
    }
    protected void btnSave_Click(object sender, EventArgs e)
    {
       
        string str = null;
        DataTable dt2 = null;
        string strOrderID = "0";
        int i = 0;
     
        connect_db();
        
       str = "insert into Orders (Order_Date,Cus_ID,Order_Name,Order_Address,Order_Tel,Order_PriceAll) " + " VALUES " + " (@sOrderDate,@sid,@sName,@sAddress,@sTel,@sss)";
        SqlCommand insert = new SqlCommand(str, dbcon.conn);
        insert.Parameters.AddWithValue("@sOrderDate", DateTime.Now.ToString("MM/dd/yyyy"));
         insert.Parameters.AddWithValue("@sid", txtid.Text);
        insert.Parameters.AddWithValue("@sName", txtName.Text);
        insert.Parameters.AddWithValue("@sAddress", txtAddress.Text);
        insert.Parameters.AddWithValue("@sTel", txtTel.Text);
        insert.Parameters.AddWithValue("@sss", lblSumTotal.Text);
        insert.ExecuteNonQuery();


        str = "SELECT Max(Order_ID) As sOrderID FROM Orders ";
        SqlDataAdapter da = new SqlDataAdapter(str, dbcon.conn);
        DataTable dt1 = new DataTable();
        da.Fill(dt1);
        if (dt1.Rows.Count > 0)
        {
            strOrderID = dt1.Rows[0]["sOrderID"].ToString();
        }
        dt2 = (DataTable)Session["myCart"];
        for (i = 0; i <= dt2.Rows.Count - 1; i++)
        { 


            str = "INSERT INTO OrderDetail (Order_ID,Pro_ID,ODt_Amount,ODt_Price) " + " VALUES " + " ('" + strOrderID + "','" + dt2.Rows[i]["Pro_ID"] + "','" + dt2.Rows[i]["ODt_Amount"] + "')";
            var _with1 = insert;
            _with1.CommandText = str;
            _with1.CommandType = CommandType.Text;
            _with1.ExecuteNonQuery();
            
           
        }
        SqlCommand cmd = new SqlCommand("update [Orders] set Order_Status='please payment' where Order_ID=" + strOrderID + "", dbcon.conn);

            
            cmd.ExecuteNonQuery();
        dbcon.closeDB();

        Session.Remove("myCart");
        Response.Redirect("Vieworder.aspx?Order_ID=" + strOrderID);

       
        }
    
        
    }

 str = "INSERT INTO OrderDetail (Order_ID,Pro_ID,ODt_Amount,ODt_Price) " + " VALUES " + " ('" + strOrderID + "','" + dt2.Rows[i]["Pro_ID"] + "','" + dt2.Rows[i]["ODt_Amount"] + "','" + strTotal + "')";