autocomplete extender in ajax

1.Add the AjaxControlToolkit.dll to your project(by Add Reference).
2.Register it in to Web.Config file.
EX:<add namespace="AjaxControlToolkit" assembly="AjaxControlToolkit" tagprefix="ajaxToolkit">
3.R.Click on your prject-->Add New Items-->Chooes-->Web Service-->AutoComplete.asmx(put name)

4.Then AutoComplete.asmx and AutoComplete.cs file is created.The

AutoComplete.cs is created on App Code .
5.Inside the AutoComplete.cs write the code and uncomment the line
as [System.Web.Script.Services.ScriptService]

EX:

using System;
using System.Web;
using System.Collections;
using System.Web.Services;
using System.Web.Services.Protocols;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;
using System.Text;
using System.Web.Script.Services;

/// <summary>
/// Summary description for AutoComplete
/// </summary>
[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
//[System.Web.Script.Services.ScriptService]
[System.Web.Script.Services.ScriptService]
public class AutoComplete : System.Web.Services.WebService
{
      [WebMethod]

    public string[] GetBlocks(string prefixText)
    {
        DataSet dtst = new DataSet();  
        SqlConnection sqlCon = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ToString());
        string strSql = "select BlockName  from BlockMaster  WHERE ltrim(rtrim(BlockName))  LIKE '%" + prefixText + "%' and DeletedFlag=0  ";
        SqlCommand sqlComd = new SqlCommand(strSql, sqlCon);
        sqlCon.Open();
        SqlDataAdapter sqlAdpt = new SqlDataAdapter();
        sqlAdpt.SelectCommand = sqlComd;
        sqlAdpt.Fill(dtst);
        string[] BlockName = new string[dtst.Tables[0].Rows.Count];
        int i = 0;
        try
        {
            foreach (DataRow rdr in dtst.Tables[0].Rows)
            {
                BlockName.SetValue(rdr["BlockName"].ToString(), i);
                i++;
            }
        }
        catch { }
        finally
        {
            sqlCon.Close();
        }
        return BlockName;

}
6.Go to View or Search Page like Block.aspx

<asp:TextBox ID="txtBlockSearch"  runat="server" CssClass="txtSearchBox"
              Width="200px"></asp:TextBox>

7.Write Inline code for AutoComplete Extender

<ajaxToolkit:AutoCompleteExtender  runat="server" ID="autoComplete1" TargetControlID="txtBlockSearch" ServicePath="AutoComplete.asmx" ServiceMethod="GetBlocks" MinimumPrefixLength="1" EnableCaching="true">
   </ajaxToolkit:AutoCompleteExtender>

8.Run the project