how to bind database data into datatable? and datatable bind in gridview? in asp.net with c# language with example

Show data in Gridview using dataset, datatable and data reader.

<%@ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" Inherits="_Default" %>





   


   

   

   
   

   
   
            Text="Using Dataset" />
            Text="Using Datatable" />
            Text="Using Datareader" />
   




using System;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.Data.OleDb;
public partial class _Default : System.Web.UI.Page
{
    OleDbConnection con;
    OleDbCommand com;
    OleDbDataAdapter oda;
    DataSet ds;
    DataTable dataTable;
   
    protected void Button1_Click(object sender, EventArgs e)
    {
        con = new OleDbConnection("Provider = Microsoft.Jet.OLEDB.4.0; Data Source = D:\\mydb.mdb");
        com = new OleDbCommand("Select * from emp", con);
        con.Open();
        oda = new OleDbDataAdapter(com);
        ds = new DataSet();
        oda.Fill(ds, "emp");
        con.Close();
        GridView1.DataMember = "emp";
        GridView1.DataSource = ds;
        GridView1.DataBind();
    }
    protected void Button2_Click(object sender, EventArgs e)
    {
        con = new OleDbConnection("Provider = Microsoft.Jet.OLEDB.4.0; Data Source = D:\\mydb.mdb");
        dataTable = new DataTable();
        com = new OleDbCommand();
        com.Connection = con;
        con.Open();
        com.CommandText = "Select * from emp";
        oda = new OleDbDataAdapter(com);
        oda.Fill(dataTable);
        con.Close();
        GridView1.DataSource = dataTable;
        GridView1.DataMember = "emp";
        GridView1.DataBind();
    }
    protected void Button3_Click(object sender, EventArgs e)
    {
        con = new OleDbConnection("Provider = Microsoft.Jet.OLEDB.4.0; Data Source = D:\\mydb.mdb");
        com = new OleDbCommand("Select * from emp", con);
        con.Open();
        OleDbDataReader reader;
        reader = com.ExecuteReader();
        GridView1.DataMember = "emp";
        GridView1.DataSource = reader;
        GridView1.DataBind();
        reader.Close();
        con.Close();
    }
}