binding data to Dynamic Grid-view Control with textbox and dropdown using dataset

i want to bind data from database to Dynamic Grid-view Control with textbox and dropdown using dataset.

i have successfully inserted data to database using this code but now i want to fetch inserted data to same grud view control. i have tried following code. but not getting ans.

SetInitialRow();
string ID = 101;

foreach (GridViewRow row in Gridview2.Rows)
            {
                
                string str1 = "Select * from VendorInvoiceDetails where Invoice_ID='" + ID + "'";
                DataSet ds1 = GEN.GetDataByQuery(str1);

                DropDownList MaterialID = (DropDownList)row.FindControl("DropDownList1");
                TextBox txtUnit = (TextBox)row.FindControl("txtUnit");
                TextBox txtRate = (TextBox)row.FindControl("txtRate");
                TextBox txtQty = (TextBox)row.FindControl("txtQuantity");
                TextBox txtTotalAmt = (TextBox)row.FindControl("txtTotalAmount");

                if (ds1.Tables[0].Rows.Count > 0)
                {
                     
                        for (int i = 0; i < ds1.Tables[0].Rows.Count; i++)
                        {
                                MaterialID.SelectedValue = ds1.Tables[0].Rows[i]["MaterialName"].ToString();
                                txtUnit.Text = ds1.Tables[0].Rows[i]["Unit"].ToString();
                                txtRate.Text = ds1.Tables[0].Rows[i]["Rate"].ToString();
                                txtQty.Text = ds1.Tables[0].Rows[i]["Quantity"].ToString();
                                txtTotalAmt.Text = ds1.Tables[0].Rows[i]["TotalAmount"].ToString();
                                AddNewRowToGrid();
                        }
                        
                }

            }



// For Setting IntialRows In Dynamic Gridview
    private void SetInitialRow()
    {
        DataTable dt = new DataTable();
        DataRow dr = null;
        dt.Columns.Add(new DataColumn("RowNumber", typeof(string)));
        dt.Columns.Add(new DataColumn("Column1", typeof(string)));
        dt.Columns.Add(new DataColumn("Column2", typeof(string)));
        dt.Columns.Add(new DataColumn("Column3", typeof(string)));
        dt.Columns.Add(new DataColumn("Column4", typeof(string)));
        dt.Columns.Add(new DataColumn("Column5", typeof(string)));

        dr = dt.NewRow();
        dr["RowNumber"] = 1;
        dr["Column1"] = string.Empty;
        dr["Column2"] = string.Empty;
        dr["Column3"] = string.Empty;
        dr["Column4"] = string.Empty;
        dr["Column5"] = string.Empty;

        dt.Rows.Add(dr);

        //Store the DataTabl e in ViewState
        ViewState["tblTender"] = dt;

        Gridview2.DataSource = dt;
        Gridview2.DataBind();
    }

    // For Adding New Rows in Dynamic GridView
    private void AddNewRowToGrid()
    {
        int rowIndex = 0;

        if (ViewState["tblTender"] != null)
        {
            DataTable dtCurrentTable = (DataTable)ViewState["tblTender"];
            DataRow drCurrentRow = null;
            if (dtCurrentTable.Rows.Count > 0)
            {
                for (int i = 1; i <= dtCurrentTable.Rows.Count; i++)
                {
                    //extract the TextBox values
                    DropDownList box1 = (DropDownList)Gridview2.Rows[rowIndex].Cells[1].FindControl("DropDownList1");
                    TextBox box2 = (TextBox)Gridview2.Rows[rowIndex].Cells[2].FindControl("txtUnit");
                    TextBox box3 = (TextBox)Gridview2.Rows[rowIndex].Cells[3].FindControl("txtRate");
                    TextBox box4 = (TextBox)Gridview2.Rows[rowIndex].Cells[4].FindControl("txtQuantity");
                    TextBox box5 = (TextBox)Gridview2.Rows[rowIndex].Cells[5].FindControl("txtTotalAmount");

                    drCurrentRow = dtCurrentTable.NewRow();
                    drCurrentRow["RowNumber"] = i + 1;

                    dtCurrentTable.Rows[i - 1]["Column1"] = box1.Text;
                    dtCurrentTable.Rows[i - 1]["Column2"] = box2.Text;
                    dtCurrentTable.Rows[i - 1]["Column3"] = box3.Text;
                    dtCurrentTable.Rows[i - 1]["Column4"] = box4.Text;
                    dtCurrentTable.Rows[i - 1]["Column5"] = box5.Text;

                    rowIndex++;
                }
                dtCurrentTable.Rows.Add(drCurrentRow);
                ViewState["tblTender"] = dtCurrentTable;

                Gridview2.DataSource = dtCurrentTable;
                Gridview2.DataBind();
            }
        }
        else
        {
            Response.Write("ViewState is null");
        }

        //Set Previous Data on Postbacks
        SetPreviousData();
    }

    // For Setting Previous Data on Postbacks
    private void SetPreviousData()
    {
        int rowIndex = 0;
        if (ViewState["tblTender"] != null)
        {
            DataTable dt = (DataTable)ViewState["tblTender"];
            if (dt.Rows.Count > 0)
            {
                for (int i = 0; i < dt.Rows.Count; i++)
                {
                    
                    DropDownList box1 = (DropDownList)Gridview2.Rows[rowIndex].Cells[1].FindControl("DropDownList1");
                    TextBox box2 = (TextBox)Gridview2.Rows[rowIndex].Cells[2].FindControl("txtUnit");
                    TextBox box3 = (TextBox)Gridview2.Rows[rowIndex].Cells[3].FindControl("txtRate");
                    TextBox box4 = (TextBox)Gridview2.Rows[rowIndex].Cells[4].FindControl("txtQuantity");
                    TextBox box5 = (TextBox)Gridview2.Rows[rowIndex].Cells[5].FindControl("txtTotalAmount");

                    box1.SelectedValue = dt.Rows[i]["Column1"].ToString();
                    box2.Text = dt.Rows[i]["Column2"].ToString();
                    box3.Text = dt.Rows[i]["Column3"].ToString();
                    box4.Text = dt.Rows[i]["Column4"].ToString();
                    box5.Text = dt.Rows[i]["Column5"].ToString();

                    rowIndex++;
                }
            }
        }
    }
    protected void ButtonAdd_Click(object sender, EventArgs e)
    {
        AddNewRowToGrid();
    }



protected void Gridview2_RowDataBound(object sender, GridViewRowEventArgs e)
    {
        try
        {

            // Binding Material
            if (e.Row.RowType == DataControlRowType.DataRow)
            {
                var ddl = (DropDownList)e.Row.FindControl("DropDownList1");
                //int CountryId = Convert.ToInt32(e.Row.Cells[0].Text);
                SqlCommand cmd = new SqlCommand("select * from MaterialMaster", con);
                SqlDataAdapter da = new SqlDataAdapter(cmd);
                DataSet ds = new DataSet();
                da.Fill(ds);
                con.Close();
                ddl.DataSource = ds;
                ddl.DataTextField = "MaterialName";
                ddl.DataValueField = "Material_Id";
                ddl.DataBind();
                ddl.Items.Insert(0, new ListItem("--Select--", "0"));
            }

        }
        catch (Exception ex)
        {
            ex.ToString();
        }
        finally
        {
            con.Close();
        }
    }