The following code will summarize the 4th columns and modify the footer row to add the summarized value to the footer row:

 

Private _sum As Decimal 

 

    Protected Sub GridView1_RowDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewRowEventArgs) Handles GridView1.RowDataBound

 

        If e.Row.RowType = DataControlRowType.DataRow Then

 

            Dim item As System.Data.DataRowView = e.Row.DataItem

 

            Dim price As Decimal = Convert.ToDecimal(item.Item(3))

 

            Me._sum = Me._sum + price

 

        ElseIf e.Row.RowType = DataControlRowType.Footer Then

 

            e.Row.Cells(3).Text = Me._sum.ToString()

 

        End If

        

    End Sub

 

Here is the ASPX code if you want to take a look at it, it use the Norhtwind database:

 

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

            DataKeyNames="ProductID" DataSourceID="SqlDataSource1" ShowFooter="True">

            <Columns>

                <asp:BoundField DataField="ProductID" HeaderText="ProductID" InsertVisible="False"

                    ReadOnly="True" SortExpression="ProductID" />

                <asp:BoundField DataField="ProductName" HeaderText="ProductName" SortExpression="ProductName" />

                <asp:BoundField DataField="UnitsInStock" HeaderText="UnitsInStock" SortExpression="UnitsInStock" />

                <asp:BoundField DataField="UnitPrice" HeaderText="UnitPrice" SortExpression="UnitPrice" />

            </Columns>

        </asp:GridView>

        <asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:NorthwindConnectionString %>"

            SelectCommand="SELECT [ProductID], [ProductName], [UnitsInStock], [UnitPrice] FROM [Alphabetical list of products]">

        </asp:SqlDataSource>

