Calculate and display Total in GridView Footer while Edit using C# and VB.Net in ASP.Net

Hi indradeo,

Check this sample. now take its reference and correct your code.

Database

For this example I have used of Northwind database that you can download using the link given below.

Download Northwind Database

HTML

<asp:GridView ID="gvOrders" runat="server" AutoGenerateColumns="false" ShowFooter="true"
    OnRowCancelingEdit="gvOrders_RowCancelingEdit" OnRowEditing="gvOrders_RowEditing">
    <Columns>
        <asp:TemplateField HeaderText="Order ID">
            <ItemTemplate>
                <asp:Label ID="lblOrderID" Text='<%#DataBinder.Eval(Container.DataItem, "OrderID") %>'
                    runat="server" />
            </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="Customer Name">
            <ItemTemplate>
                <asp:Label ID="lblCustomerID" Text='<%#DataBinder.Eval(Container.DataItem, "CustomerID") %>'
                    runat="server" />
            </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="Price">
            <ItemTemplate>
                <asp:Label ID="lblPrice" Text='<%#DataBinder.Eval(Container.DataItem, "Freight") %>'
                    runat="server" />
            </ItemTemplate>
            <EditItemTemplate>
                <asp:TextBox ID="txtPrice" Text='<%# DataBinder.Eval(Container.DataItem,"Freight") %>'
                    runat="server" OnTextChanged="ChangePrice" AutoPostBack="true" />
            </EditItemTemplate>
        </asp:TemplateField>
        <asp:CommandField ShowEditButton="true" ShowCancelButton="true" ButtonType="Button" />
    </Columns>
</asp:GridView>

Namespaces

C#

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

VB.Net

Imports System.Configuration
Imports System.Data
Imports System.Data.SqlClient

Code

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        this.BindOrders();
    }
}    

protected void ChangePrice(object sender, EventArgs e)
{
    string price = (sender as TextBox).Text;
    int index = gvOrders.EditIndex;
    decimal total = 0;
    for (int i = 0; i < gvOrders.Rows.Count; i++)
    {
        if (i != index)
        {
            total += Convert.ToDecimal((gvOrders.Rows[i].FindControl("lblPrice") as Label).Text);
        }
    }
    total += Convert.ToDecimal(price);
    gvOrders.FooterRow.Cells[2].Text = total.ToString("N2");
}

protected void gvOrders_RowEditing(object sender, GridViewEditEventArgs e)
{
    this.gvOrders.EditIndex = e.NewEditIndex;
    this.BindOrders();
}

protected void gvOrders_RowCancelingEdit(object sender, GridViewCancelEditEventArgs e)
{
    this.gvOrders.EditIndex = -1;
    this.BindOrders();
}

private void BindOrders()
{
    using (SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["constr"].ConnectionString))
    {
        using (SqlCommand cmd = new SqlCommand("SELECT TOP 3 OrderID,CustomerID,Freight FROM ORDERS", con))
        {
            cmd.CommandType = CommandType.Text;
            using (SqlDataAdapter sda = new SqlDataAdapter())
            {
                sda.SelectCommand = cmd;
                DataTable dt = new DataTable();
                sda.Fill(dt);
                this.gvOrders.DataSource = dt;
                this.gvOrders.DataBind();

                decimal grandTotal = dt.AsEnumerable().Sum(row => row.Field<decimal>("Freight"));
                gvOrders.FooterRow.Cells[1].Text = "Grand Total";
                gvOrders.FooterRow.Cells[2].Text = grandTotal.ToString("N2");
            }
        }
    }
}

VB.Net

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    If Not Me.IsPostBack Then
        Me.BindOrders()
    End If
End Sub

Protected Sub ChangePrice(ByVal sender As Object, ByVal e As EventArgs)
    Dim price As String = (TryCast(sender, TextBox)).Text
    Dim index As Integer = gvOrders.EditIndex
    Dim total As Decimal = 0
    For i As Integer = 0 To gvOrders.Rows.Count - 1

        If i <> index Then
            total += Convert.ToDecimal((TryCast(gvOrders.Rows(i).FindControl("lblPrice"), Label)).Text)
        End If
    Next

    total += Convert.ToDecimal(price)
    gvOrders.FooterRow.Cells(2).Text = total.ToString("N2")
End Sub

Protected Sub gvOrders_RowEditing(ByVal sender As Object, ByVal e As GridViewEditEventArgs)
    Me.gvOrders.EditIndex = e.NewEditIndex
    Me.BindOrders()
End Sub

Protected Sub gvOrders_RowCancelingEdit(ByVal sender As Object, ByVal e As GridViewCancelEditEventArgs)
    Me.gvOrders.EditIndex = -1
    Me.BindOrders()
End Sub

Private Sub BindOrders()
    Using con As SqlConnection = New SqlConnection(ConfigurationManager.ConnectionStrings("constr").ConnectionString)
        Using cmd As SqlCommand = New SqlCommand("SELECT TOP 3 OrderID,CustomerID,Freight FROM ORDERS", con)
            cmd.CommandType = CommandType.Text
            Using sda As SqlDataAdapter = New SqlDataAdapter()
                sda.SelectCommand = cmd
                Dim dt As DataTable = New DataTable()
                sda.Fill(dt)
                Me.gvOrders.DataSource = dt
                Me.gvOrders.DataBind()
                Dim grandTotal As Decimal = dt.AsEnumerable().Sum(Function(row) row.Field(Of Decimal)("Freight"))
                gvOrders.FooterRow.Cells(1).Text = "Grand Total"
                gvOrders.FooterRow.Cells(2).Text = grandTotal.ToString("N2")
            End Using
        End Using
    End Using
End Sub

Screenshot