Insert,Update,Delete and Add by the GridView Commnd Event

1. ShowFooter="true" // This Property will set for Footer Reason

Database Design

 C# Code
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Configuration;
using System.Data;
using System.Data.SqlClient;

public partial class Gridview_insertupdateDelete : System.Web.UI.Page
{
    SqlConnection con;
    SqlCommand cmd;
    SqlDataAdapter da;
    protected void Page_Load(object sender, EventArgs e)
    {
        con = new SqlConnection(ConfigurationManager.ConnectionStrings["Satya"].ToString());
        con.Open();
        if (!IsPostBack)
        {
            GetData();
        }
    }
    public void GetData()
    {
        if (con.State == ConnectionState.Closed)
        {
            con.Open();
        }
     
        da = new SqlDataAdapter("Select * from Demo",con);
        DataTable dt = new DataTable();
        da.Fill(dt);
        GridView1.DataSource = dt;
        GridView1.DataBind();
        con.Close();
    }
    protected void GridView1_RowEditing(object sender, GridViewEditEventArgs e)
    {
        GridView1.EditIndex = e.NewEditIndex;
        GetData();
    }
    protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
    {
        int a = Convert.ToInt32(GridView1.DataKeys[e.RowIndex].Value.ToString());
        string b = GridView1.DataKeys[e.RowIndex].Values["Name"].ToString();
        TextBox tb = (TextBox)GridView1.Rows[e.RowIndex].FindControl("TextBox2");
        TextBox tc = (TextBox)GridView1.Rows[e.RowIndex].FindControl("TextBox3");
        if (con.State == ConnectionState.Closed)
        {
            con.Open();
        }
        cmd = new SqlCommand("Update demo set Name='"+tb.Text+"',Address='"+tc.Text+"' where roll="+a,con);
        cmd.ExecuteNonQuery();
            con.Close();
            GridView1.EditIndex = -1;
            GetData();
    }
    protected void GridView1_RowDeleting(object sender, GridViewDeleteEventArgs e)
    {
        int a = Convert.ToInt32(GridView1.DataKeys[e.RowIndex].Value.ToString());
        //string b = GridView1.DataKeys[e.RowIndex].Value.ToString();
        TextBox tb = (TextBox)GridView1.Rows[e.RowIndex].FindControl("TextBox2");
        TextBox tc = (TextBox)GridView1.Rows[e.RowIndex].FindControl("TextBox3");
        if (con.State == ConnectionState.Closed)
        {
            con.Open();
        }
        cmd = new SqlCommand("Delete from Demo where Roll='"+a.ToString()+"'",con);
        cmd.ExecuteNonQuery();
        con.Close();
        GetData();
    }
    protected void GridView1_RowCancelingEdit(object sender, GridViewCancelEditEventArgs e)

    {
        GridView1.EditIndex = -1;
        GetData();
    }
    protected void GridView1_SelectedIndexChanged(object sender, EventArgs e)
    {


    }

  
    protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)
    {

        if (e.CommandName.Equals("AddNew"))
        {
            TextBox txtUsrname = (TextBox)GridView1.FooterRow.FindControl("TextBox4");
            TextBox txtCity = (TextBox)GridView1.FooterRow.FindControl("TextBox5");
            TextBox txtDesgnation = (TextBox)GridView1.FooterRow.FindControl("TextBox6");
            if (con.State == ConnectionState.Closed)
            {
                con.Open();
            }
            SqlCommand cmd =
            new SqlCommand(
            "insert into Demo(Roll,Name,Address) values('" + txtUsrname.Text + "','" +
            txtCity.Text + "','" + txtDesgnation.Text + "')", con);
            int result = cmd.ExecuteNonQuery();
            con.Close();
            if (result == 1)
            {
            
                Response.Write("inserted succefully");
                GetData();
               // lblresult.ForeColor = Color.Green;
               // lblresult.Text = txtUsrname.Text + " Details inserted successfully";
            }
            else
            {
                Response.Write(" data not inserted succefully");
                GetData();
                //lblresult.ForeColor = Color.Red;
                //lblresult.Text = txtUsrname.Text + " Details not inserted";
            }
        }

    }
}

 Source Code 
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Gridview insertupdateDelete.aspx.cs" Inherits="Gridview_insertupdateDelete" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
   
    </div>
   
        <asp:GridView ID="GridView1" runat="server"
        style="position:absolute; top: 75px; left: 256px;"
        AutoGenerateColumns="False" onrowcancelingedit="GridView1_RowCancelingEdit"
        onrowdeleting="GridView1_RowDeleting" onrowediting="GridView1_RowEditing"  ShowFooter="true"
        onrowupdating="GridView1_RowUpdating" DataKeyNames="Roll,Name"
        onrowcommand="GridView1_RowCommand">
            <Columns>
                <asp:CommandField ShowEditButton="True" />
                <asp:CommandField ShowDeleteButton="True" />
                <asp:TemplateField>
                <FooterTemplate>
                  <asp:Button ID="Button1" runat="server" Text="AddNew" CommandName="AddNew" />
                  
                </FooterTemplate>
              
                </asp:TemplateField>

                <asp:TemplateField HeaderText="Roll">            
                    <FooterTemplate>
                        <asp:TextBox ID="TextBox4" runat="server"></asp:TextBox>
                    </FooterTemplate>
                <ItemTemplate>
                 <asp:TextBox ID="TextBox1" runat="server" Text='<%#Eval("Roll")%>'>
                    </asp:TextBox>
                </ItemTemplate>                  
                </asp:TemplateField>
                <asp:TemplateField HeaderText="Name">
                    <FooterTemplate>

                        <asp:TextBox ID="TextBox5" runat="server"></asp:TextBox>
                    </FooterTemplate>
                <ItemTemplate>
                 <asp:TextBox ID="TextBox2" runat="server" Text='<%#Eval("Name")%>'>
                    </asp:TextBox>
                </ItemTemplate>
                </asp:TemplateField>
                <asp:TemplateField HeaderText="Address" >
                    <FooterTemplate>
                        <asp:TextBox ID="TextBox6" runat="server"></asp:TextBox>
                    </FooterTemplate>
                <ItemTemplate>
                 <asp:TextBox ID="TextBox3" runat="server" Text='<%#Eval("Address")%>'>
                    </asp:TextBox>
                </ItemTemplate>
                </asp:TemplateField>
            </Columns>         


        </asp:GridView>
   
    </form>
</body>
</html>
Page Design