In this article I will explain with an example, how to display sum of Columns total (Grand Total) in GridView Footer in ASP.Net using C# and VB.Net.
The GridView has paging enabled and the sum of values of a particular column on each page will be displayed in the GridView Footer Row as Grand Total.
 
 

Database

Here I am making use of Microsoft’s Northwind Database. You can download it from here.
Download and install Northwind Database
 
 

HTML Markup

The HTML Markup consists of:
GridView - For displaying data.
In order to implement Paging in GridView, AllowPaging property is set to true and OnPageIndexChanging event has been assigned.
The GridView consists of three BoundField columns.
<asp:GridView ID="gvProducts" runat="server" AutoGenerateColumns="false" AllowPaging="true"
    OnPageIndexChanging="OnPageIndexChanging" ShowFooter="true">
    <Columns>
        <asp:BoundField DataField="OrderID" HeaderText="Order ID" ItemStyle-Width="60" />
        <asp:BoundField DataField="ProductName" HeaderText="Product Name" ItemStyle-Width="210" />
        <asp:BoundField DataField="Price" HeaderText="Price" ItemStyle-Width="60" DataFormatString="{0:N2}"
            ItemStyle-HorizontalAlign="Right" />
    </Columns>
</asp:GridView>
 
 

Namespaces

You will need to import the following namespaces.
C#
using System.Linq;
using System.Data;
using System.Configuration;
using System.Data.SqlClient;
 
VB.Net
Imports System.Linq
Imports System.Data
Imports System.Configuration
Imports System.Data.SqlClient
 
 

Binding the GridView and calculating the Sum of Columns Total

Inside the Page_Load event handler, the BindGrid method is called.
Inside the BindGrid method, the Query gets records of Orders along with Products and their respective costs.
After that, the connection string is read from the Web.Config file.
Note: For more details on how to read connection string from Web.Config file, please refer my article Read or Write Connection Strings in Web.Config file using ASP.Net using C# and VB.Net.
 
Then, the records are fetched from the Customers Table of SQL Server database using SqlDataAdapter and copied to DataTable object using Fill method.
Finally, the DataTable is assigned to the DataSource property of GridView and the GridView is populated, then Sum of the Price column is calculated and displayed in the Footer Row’s Cell as Grand Total.
C#
protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        this.BindGrid();
    }
}
 
private void BindGrid()
{
    string sql = "SELECT TOP 30 OrderID,";
    sql += "(SELECT ProductName FROM Products WHERE ProductID = details.ProductId) ProductName,";
    sql += "(Quantity * UnitPrice) Price";
    sql += " FROM [Order Details] details";
    sql += " ORDER BY OrderID";
    string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
    using (SqlConnection con = new SqlConnection(constr))
    {
        using (SqlCommand cmd = new SqlCommand(sql, con))
        {
            using (SqlDataAdapter sda = new SqlDataAdapter(cmd))
            {
                using (DataTable dt = new DataTable())
                {
                    sda.Fill(dt);
                    gvProducts.DataSource = dt;
                    gvProducts.DataBind();
 
                    //Calculate Sum and display in Footer Row
                    decimal total = dt.AsEnumerable().Sum(row => row.Field<decimal>("Price"));
                    gvProducts.FooterRow.Cells[1].Text = "Total";
                    gvProducts.FooterRow.Cells[1].HorizontalAlign = HorizontalAlign.Right;
                    gvProducts.FooterRow.Cells[2].Text = total.ToString("N2");
                }
            }
        }
    }
}
 
VB.Net
Protected Sub Page_Load(sender As Object, e As EventArgs) Handles Me.Load
    If Not Me.IsPostBack Then
        Me.BindGrid()
    End If
End Sub
 
Private Sub BindGrid()
    Dim sql As String = "SELECT TOP 30 OrderID,"
    sql += "(SELECT ProductName FROM Products WHERE ProductID = details.ProductId) ProductName,"
    sql += "(Quantity * UnitPrice) Price"
    sql += " FROM [Order Details] details"
    sql += " ORDER BY OrderID"
    Dim constr As String = ConfigurationManager.ConnectionStrings("constr").ConnectionString
    Using con As New SqlConnection(constr)
        Using cmd As New SqlCommand(sql)
            Using sda As New SqlDataAdapter()
                cmd.Connection = con
                sda.SelectCommand = cmd
                Using dt As New DataTable()
                    sda.Fill(dt)
                    gvProducts.DataSource = dt
                    gvProducts.DataBind()
 
                    'Calculate Sum and display in Footer Row
                    Dim total As Decimal = dt.AsEnumerable().Sum(Function(row) row.Field(Of Decimal)("Price"))
                    gvProducts.FooterRow.Cells(1).Text = "Total"
                    gvProducts.FooterRow.Cells(1).HorizontalAlign = HorizontalAlign.Right
                    gvProducts.FooterRow.Cells(2).Text = total.ToString("N2")
                End Using
            End Using
        End Using
    End Using
End Sub
 
 

Implementing Paging in GridView

Inside the OnPageIndexChanging event handler, the PageIndex property of the GridView is set with the new PageIndex and the BindGrid method is called.
C#
protected void OnPageIndexChanging(object sender, GridViewPageEventArgs e)
{
    gvProducts.PageIndex = e.NewPageIndex;
    this.BindGrid();
}
 
VB.Net
Protected Sub OnPageIndexChanging(sender As Object, e As GridViewPageEventArgs)
    gvProducts.PageIndex = e.NewPageIndex
    Me.BindGrid()
End Sub
 
 

Screenshot

Display sum of Columns total in GridView Footer in ASP.Net using C# and VB.Net
 
 

Demo

View Demo
 
 

Downloads

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