GridView1 RowDataBound (DataControlRowType.Footer)

<asp:GridView ID="GridView1" runat="server" AllowPaging="True" AllowSorting="True" AutoGenerateColumns="False"

    CssClass="table table-striped table-bordered table-hover" DataKeyNames="slide_ID" DataSourceID="LinqDataSource1" GridLines="None">

    <Columns>

        <asp:BoundField DataField="slide_type" HeaderText="ประเภท" SortExpression="slide_type">

        <HeaderStyle Width="150px" />

        <ItemStyle HorizontalAlign="Center" />

        </asp:BoundField>

        <asp:BoundField DataField="slide_img" HeaderText="ตำแหน่งรูปภาพ" SortExpression="slide_img" />

        <asp:CommandField ButtonType="Button" SelectText="แก้ไข" ShowSelectButton="True" />

       <asp:TemplateField >

           <ItemTemplate >

               <asp:HiddenField ID="hddslide_ID" runat="server" Value ='<%# Eval("slide_ID")%>'  />

           </ItemTemplate>

       </asp:TemplateField>

    </Columns>

</asp:GridView>

<div class="pull-right well" >

    <div class =""> ผลรวม :

            <asp:Literal ID="ltrSum" runat="server"></asp:Literal>

        </div>

</div>

   

**********************************************************

Private Sub GridView1_RowDataBound(sender As Object, e As GridViewRowEventArgs) Handles GridView1.RowDataBound

        If e.Row.RowType = DataControlRowType.DataRow Then

            Try

                Dim hddslide_ID As HiddenField = CType(e.Row.FindControl("hddslide_ID"), HiddenField)

                sum = sum + Val(hddslide_ID.Value)

            Catch ex As Exception

            End Try

        End If

        If e.Row.RowType = DataControlRowType.Footer Then

            ltrSum.Text = sum

        End If

    End Sub