Grid View DML using tamplate Fully Customized

*****************Design************
  <form id="form1" runat="server">
    <div>
    </div>
    <asp:ObjectDataSource ID="ObjectDataSource1" runat="server"
        DataObjectTypeName="BE.BELab" DeleteMethod="Deletelab" InsertMethod="insertlab"
        SelectMethod="show" TypeName="BLL.LabBLL" UpdateMethod="Updatelab">
    </asp:ObjectDataSource>
    <asp:GridView ID="GridView1" runat="server"
        DataSourceID="ObjectDataSource1" DataKeyNames="ID" Height="190px"
        ShowFooter="True" AlternatingRowStyle-BackColor="SeaGreen"
        HeaderStyle-BackColor="Aqua" AutoGenerateColumns="False"
        FooterStyle-BackColor="Azure">
<AlternatingRowStyle BackColor="SeaGreen"></AlternatingRowStyle>
        <Columns>
            <asp:TemplateField ShowHeader="False">
                <EditItemTemplate>
                    <asp:LinkButton ID="LinkButton1" runat="server" CausesValidation="True"
                        CommandName="Update" Text="Update"></asp:LinkButton>
                    &nbsp;<asp:LinkButton ID="LinkButton2" runat="server" CausesValidation="False"
                        CommandName="Cancel" Text="Cancel"></asp:LinkButton>
                </EditItemTemplate>
                <ItemTemplate>
                    <asp:LinkButton ID="LinkButton1" runat="server" CausesValidation="False"
                        CommandName="Edit" Text="Edit"></asp:LinkButton>
                    &nbsp;<asp:LinkButton ID="LinkButton2" runat="server" CausesValidation="False"
                        CommandName="Delete" Text="Delete"></asp:LinkButton>
                </ItemTemplate>
                <FooterTemplate>
               
                <asp:Button ID="btnadd" runat="server" Text="Add" OnClick="Insert_into_Grid" />
               
                </FooterTemplate>
              
            </asp:TemplateField>
      
          
            <asp:TemplateField HeaderText="ID" SortExpression="ID">
                <EditItemTemplate>
                    <asp:TextBox ID="TextBox1" runat="server" Text='<%# Bind("ID") %>'></asp:TextBox>
                </EditItemTemplate>
                <ItemTemplate>
                    <asp:Label ID="Label1" runat="server" Text='<%# Bind("ID") %>'></asp:Label>
                </ItemTemplate>
                <FooterTemplate>
                <asp:TextBox ID="txtID" runat="server"></asp:TextBox>
                </FooterTemplate>
            </asp:TemplateField>
            <asp:TemplateField HeaderText="Assignment" SortExpression="Assignment">
                <EditItemTemplate>
                    <asp:TextBox ID="TextBox2" runat="server" Text='<%# Bind("Assignment") %>'></asp:TextBox>
                </EditItemTemplate>
                <ItemTemplate>
                    <asp:Label ID="Label2" runat="server" Text='<%# Bind("Assignment") %>'></asp:Label>
                </ItemTemplate>
                <FooterTemplate>
                <asp:TextBox ID="txtAssignment" runat="server"></asp:TextBox>
                </FooterTemplate>
           
            </asp:TemplateField>
            <asp:TemplateField HeaderText="RollNo" SortExpression="RollNo">
                <EditItemTemplate>
                    <asp:DropDownList ID="DropDownList1" runat="server"
                        DataSourceID="SqlDataSource1" DataTextField="StdName"
                        DataValueField="StdRollNo" SelectedValue='<%# Bind("RollNo") %>'>
                    </asp:DropDownList>
                    <asp:SqlDataSource ID="SqlDataSource1" runat="server"
                        ConnectionString="<%$ ConnectionStrings:DBStudentTestConnectionString %>"
                        SelectCommand="SELECT [StdName], [StdRollNo] FROM [tblStudent]">
                    </asp:SqlDataSource>
                </EditItemTemplate>
                <ItemTemplate>
                <asp:HiddenField ID="Hd1" runat="server" Value='<%# Bind("RollNo") %>' />
                    <asp:DropDownList ID="DropDownList1" runat="server"
                        DataSourceID="SqlDataSource1" DataTextField="StdName"
                        DataValueField="StdRollNo" SelectedValue='<%# Bind("RollNo") %>'>
                    </asp:DropDownList>
                    <asp:SqlDataSource ID="SqlDataSource1" runat="server"
                        ConnectionString="<%$ ConnectionStrings:DBStudentTestConnectionString %>"
                        SelectCommand="SELECT [StdName], [StdRollNo] FROM [tblStudent]">
                    </asp:SqlDataSource>
                </ItemTemplate>
               <FooterTemplate>
              
                <asp:DropDownList ID="DropDownList1" runat="server"
                        DataSourceID="SqlDataSource1" DataTextField="StdName"
                        DataValueField="StdRollNo" SelectedValue='<%# Bind("RollNo") %>'>
                    </asp:DropDownList>

                      <asp:SqlDataSource ID="SqlDataSource1" runat="server"
                        ConnectionString="<%$ ConnectionStrings:DBStudentTestConnectionString %>"
                        SelectCommand="SELECT [StdName], [StdRollNo] FROM [tblStudent]">
                    </asp:SqlDataSource>
              
               </FooterTemplate>
              
            </asp:TemplateField>
        </Columns>

<FooterStyle BackColor="Azure"></FooterStyle>

<HeaderStyle BackColor="Aqua"></HeaderStyle>
    </asp:GridView>


    <div>
   


   
    </div>


    </form>
**************************back coding************
 protected void Insert_into_Grid(object sender, EventArgs e)
        {
            Control control = null;

            if (GridView1.FooterRow != null)
            {

                control = GridView1.FooterRow;

            }
            else
            {
                control = GridView1.Controls[0].Controls[0];

            }

            Int32 ID = Convert.ToInt32((control.FindControl("txtID") as TextBox).Text);
            string txtAssignment = (control.FindControl("txtAssignment") as TextBox).Text;
            string Rollno = (control.FindControl("DropDownList1") as DropDownList).SelectedValue;
            BELab be = new BELab();
            be.ID = ID;
            be.RollNo = Rollno;
            be.Assignment = txtAssignment;
            new LabBLL().insertlab(be);
            GridView1.DataBind();

        }