GRID VIEW EDITING

 <asp:GridView ID="gvModification" runat="server" EmptyDataText="No Record" AutoGenerateColumns="False"
                        DataKeyNames="id" OnRowCancelingEdit="gvModification_RowCancelingEdit" OnRowCommand="gvModification_RowCommand"
                        OnRowDataBound="gvModification_RowDataBound" OnRowDeleting="gvModification_RowDeleting"
                        OnRowEditing="gvModification_RowEditing" OnRowUpdating="gvModification_RowUpdating"
                        Style="font-family: Arial, Helvetica, sans-serif; font-size: small" Width="100%"
                        CellPadding="4" ForeColor="#333333" GridLines="None">
                        <FooterStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" />
                        <RowStyle BackColor="#F7F6F3" ForeColor="#333333" />
                        <Columns>
                            <asp:TemplateField HeaderText="Date">
                                <ItemTemplate>
                                    <asp:Label ID="lblDate" runat="server" Text='<%# Eval("DATE")%>'></asp:Label>
                                </ItemTemplate>
                                <EditItemTemplate>
                                    <asp:TextBox ID="txtDate" Width="150" runat="server" Text='<%# Eval("DATE") %>'></asp:TextBox>
                                    <cc1:CalendarExtender ID="CalendarExtender1" Format="dd/MM/yyyy" runat="server" TargetControlID="txtDate">
                                    </cc1:CalendarExtender>
                                </EditItemTemplate>
                            </asp:TemplateField>
                            <asp:TemplateField HeaderText="ITEM">
                                <ItemTemplate>
                                    <asp:Label ID="lblItem" runat="server" Text='<%# Eval("ItemName") %>'></asp:Label>
                                </ItemTemplate>
                                <EditItemTemplate>
                                    <asp:DropDownList ID="ddlItem" runat="server" DataSourceID="SqlDataSource1" SelectedValue='<%# Bind("ITEMCODE") %>'
                                        DataTextField="ITEMNAME" DataValueField="ITEMCODE">
                                    </asp:DropDownList>
                                </EditItemTemplate>
                            </asp:TemplateField>
                            <asp:TemplateField>
                                <ItemTemplate>
                                    <asp:HiddenField ID="hnfItemCode" runat="server" Value='<%#Eval("Itemcode") %>' Visible="false" />
                                </ItemTemplate>
                            </asp:TemplateField>
                            <asp:TemplateField HeaderText="Quantity" HeaderStyle-HorizontalAlign="Right" ItemStyle-HorizontalAlign="Right">
                                <ItemTemplate>
                                    <asp:Label ID="lblQty" runat="server" Text='<%# Eval("Qty") %>'></asp:Label>
                                </ItemTemplate>
                                <EditItemTemplate>
                                    <asp:TextBox ID="txtQty" Width="50" runat="server" Text='<%# Eval("Qty") %>'></asp:TextBox>
                                </EditItemTemplate>
                            </asp:TemplateField>
                            <asp:TemplateField>
                                <ItemTemplate>
                                    <asp:HiddenField ID="hnChallan" runat="server" Value='<%# Eval("mvoucher") %>' />
                                </ItemTemplate>
                            </asp:TemplateField>
                            <asp:TemplateField>
                                <ItemTemplate>
                                    <asp:LinkButton ID="lbEdit" runat="server" CommandName="Edit" Text="Edit">
                                    </asp:LinkButton>
                                    <asp:LinkButton ID="lbDelete" runat="server" CommandArgument='<%#Bind("ID") %>' CommandName="Delete"
                                        Text="Delete"></asp:LinkButton>
                                </ItemTemplate>
                                <EditItemTemplate>
                                    <asp:LinkButton ID="lbUpdate" runat="server" CommandName="Update" Text="Update"></asp:LinkButton>
                                    <asp:LinkButton ID="lbCancel" runat="server" CommandName="Cancel" Text="Cancel"></asp:LinkButton>
                                </EditItemTemplate>
                            </asp:TemplateField>
                        </Columns>
                        <PagerStyle BackColor="#284775" ForeColor="White" HorizontalAlign="Center" />
                        <SelectedRowStyle BackColor="#E2DED6" Font-Bold="True" ForeColor="#333333" />
                        <HeaderStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" CssClass="grd" />
                        <EditRowStyle BackColor="#999999" />
                        <AlternatingRowStyle BackColor="White" ForeColor="#284775" />
                    </asp:GridView>

c#


    protected void gvModification_RowCommand(object sender, GridViewCommandEventArgs e)
    {
        if (e.CommandName == "Delete")
        {
            int id = Convert.ToInt32(e.CommandArgument);
            objrequest.id = id.ToString();
            objrequest.delrecord1();
            Page.ClientScript.RegisterStartupScript(typeof(Page), "Deleted", "alert('Deleted ')", true);
            modification();
            try
            {
                if (gvModification.Rows.Count <= 0)
                {
                    objrequest.updatehead();
                    DataSet ds = RealStateClass.Requestpage.getrerqestion(txtrequestNo.Text.ToString());
                    if (ds.Tables[0].Rows.Count > 0)
                    { }
                    else
                    {
                        objrequest.CINVNO = txtrequestNo.Text.ToString();
                        objrequest.delrecord2();
                    }
                }
            }
            catch (Exception) { }
            finally { }

        }

    }
    protected void gvModification_RowDeleting(object sender, GridViewDeleteEventArgs e)
    {

    }
    protected void gvModification_RowUpdating(object sender, GridViewUpdateEventArgs e)
    {

        string st1 = ((TextBox)gvModification.Rows[e.RowIndex].Cells[0].FindControl("txtDate")).Text;
        string st2 = ((DropDownList)gvModification.Rows[e.RowIndex].Cells[2].FindControl("ddlItem")).SelectedItem.Value;
        string st3 = ((TextBox)gvModification.Rows[e.RowIndex].Cells[1].FindControl("txtQty")).Text;
        string st4 = ((HiddenField)gvModification.Rows[e.RowIndex].Cells[3].FindControl("hnChallan")).Value;
        DateTime dt2;
        dt2 = Convert.ToDateTime(st1, System.Globalization.CultureInfo.CreateSpecificCulture("en-CA"));
        objrequest.Date = dt2;
        objrequest.ItemCode = st2.ToString();
        objrequest.Quantity = st3.ToString();
        objrequest.id = gvModification.DataKeys[e.RowIndex].Values["id"].ToString();
        objrequest.updaterequestmodi();
        gvModification.EditIndex = -1;
        modification();


    }
    protected void gvModification_RowDataBound(object sender, GridViewRowEventArgs e)
    {
    }
    protected void gvModification_RowCancelingEdit(object sender, GridViewCancelEditEventArgs e)
    {
        gvModification.EditIndex = -1;
        modification();

    }
    protected void gvModification_RowEditing(object sender, GridViewEditEventArgs e)
    {
        gvModification.EditIndex = e.NewEditIndex;
        modification();

    }