Display sum of ASP.Net GridView column total with paging and filtering using C# and VB.Net

Hi tutovavera,

Check this example. Now please take its reference and correct your code.

For this example I am making use of the Microsoft's Northwind Database. You can download from the below link.

Install Microsoft Northwind and Pubs Sample databases in SQL Server Management Studio

HTML

<div align="center">
    Order ID:&nbsp;
    <asp:TextBox ID="txtOrderId" OnTextChanged="OnTextChanged" AutoPostBack="true" runat="server" />
    <br />
    <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="false" AllowPaging="true"
        PageSize="2" OnRowDataBound="OnDataBound" OnPageIndexChanging="OnPageIndexChanging"
        ShowFooter="true">
        <Columns>
            <asp:BoundField DataField="OrderID" HeaderText="Order ID" />
            <asp:BoundField DataField="ProductName" HeaderText="Product Name" />
            <asp:BoundField DataField="Price" HeaderText="Price" DataFormatString="{0:N2}" />
        </Columns>
    </asp:GridView>
    <br />
    <b>Grand Total:</b>&nbsp;<asp:Label ID="txtGrandTotal" runat="server" />
</div>

Namespaces

C#

using System.Data;
using System.Configuration;
using System.Data.SqlClient;

VB.Net

Imports System.Data.SqlClient
Imports System.Data

Code

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        this.BindGrid();
    }
}
private void BindGrid(string orderId = null)
{
    string query = "SELECT TOP 5 OrderID,";
    query += "(SELECT ProductName FROM Products WHERE ProductID = details.ProductId) ProductName,";
    query += "(Quantity * UnitPrice) Price";
    query += " FROM [Order Details] details";
    if (!string.IsNullOrEmpty(orderId))
    {
        query += " WHERE OrderID = " + orderId;
    }
    query += " ORDER BY OrderID";
    string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
    using (SqlConnection con = new SqlConnection(constr))
    {
        using (SqlCommand cmd = new SqlCommand(query))
        {
            using (SqlDataAdapter sda = new SqlDataAdapter())
            {
                cmd.Connection = con;
                sda.SelectCommand = cmd;
                using (DataTable dt = new DataTable())
                {
                    sda.Fill(dt);
                    GridView1.DataSource = dt;
                    GridView1.DataBind();
                    txtGrandTotal.Text = dt.AsEnumerable().Sum(row => row.Field<decimal>("Price")).ToString("N2");
                }
            }
        }
    }
}
protected void OnTextChanged(object sender, EventArgs e)
{
    BindGrid(txtOrderId.Text);
}
decimal total = 0;
protected void OnDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.DataRow)
    {
        total = total + Convert.ToDecimal(e.Row.Cells[2].Text);
    }
    if (e.Row.RowType == DataControlRowType.Footer)
    {
        e.Row.Cells[1].Text = "<b>Sub Total:</b>";
        e.Row.Cells[1].HorizontalAlign = HorizontalAlign.Right;
        e.Row.Cells[2].Text = total.ToString("N2");
    }
}
protected void OnPageIndexChanging(object sender, GridViewPageEventArgs e)
{
    GridView1.PageIndex = e.NewPageIndex;
    BindGrid(txtOrderId.Text);
}

VB.Net

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    If Not Me.IsPostBack Then
        Me.BindGrid()
    End If
End Sub
Private Sub BindGrid(Optional ByVal orderId As String = Nothing)
    Dim query As String = "SELECT TOP 5 OrderID,"
    query += "(SELECT ProductName FROM Products WHERE ProductID = details.ProductId) ProductName,"
    query += "(Quantity * UnitPrice) Price"
    query += " FROM [Order Details] details"
    If Not String.IsNullOrEmpty(orderId) Then
        query += " WHERE OrderID = " & orderId
    End If

    query += " ORDER BY OrderID"
    Dim constr As String = ConfigurationManager.ConnectionStrings("constr").ConnectionString
    Using con As SqlConnection = New SqlConnection(constr)
        Using cmd As SqlCommand = New SqlCommand(query)
            Using sda As SqlDataAdapter = New SqlDataAdapter()
                cmd.Connection = con
                sda.SelectCommand = cmd
                Using dt As DataTable = New DataTable()
                    sda.Fill(dt)
                    GridView1.DataSource = dt
                    GridView1.DataBind()
                    txtGrandTotal.Text = dt.AsEnumerable().Sum(Function(row) row.Field(Of Decimal)("Price")).ToString("N2")
                End Using
            End Using
        End Using
    End Using
End Sub
Protected Sub OnTextChanged(ByVal sender As Object, ByVal e As EventArgs)
    BindGrid(txtOrderId.Text)
End Sub
Private total As Decimal = 0
Protected Sub OnDataBound(ByVal sender As Object, ByVal e As GridViewRowEventArgs)
    If e.Row.RowType = DataControlRowType.DataRow Then
        total = total + Convert.ToDecimal(e.Row.Cells(2).Text)
    End If

    If e.Row.RowType = DataControlRowType.Footer Then
        e.Row.Cells(1).Text = "<b>Sub Total:</b>"
        e.Row.Cells(1).HorizontalAlign = HorizontalAlign.Right
        e.Row.Cells(2).Text = total.ToString("N2")
    End If
End Sub
Protected Sub OnPageIndexChanging(ByVal sender As Object, ByVal e As GridViewPageEventArgs)
    GridView1.PageIndex = e.NewPageIndex
    BindGrid(txtOrderId.Text)
End Sub

Screenshot