Step 1 : Take a TextBox , AutoCompleteExtender
<asp:TextBox runat="server" ID="txtInput" Width="300" />
<cc1:AutoCompleteExtender runat="server" ID="AutoComplete1"
TargetControlID="txtInput"
ServiceMethod="GetNames"
ServicePath="WebService.asmx"
MinimumPrefixLength="1"
CompletionInterval="1000"
EnableCaching="true"
CompletionSetCount="20"/>
Step 2 : Add ScriptManager on page with <Services> tag
<asp:ScriptManager ID="ScriptManager1" runat="server">
<Services>
<asp:ServiceReference Path="~/WebService.asmx" />
</Services>
</asp:ScriptManager>
Step 3: Add a Webservice file in your website by Right click on website->Add new Item ->Web Service and add this code inside it..
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Services;
using System.Configuration;
using System.Data;
using System.Data.SqlClient;
using System.Web.Services;
[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
[System.Web.Script.Services.ScriptService]
public class WebService : System.Web.Services.WebService
{
public WebService()
{
}
[WebMethod]
public string[] GetNames(string prefixText, int count)
{
List<string> items = new List<string>(count);
DataSet ds = new DataSet();
string cs = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
using (SqlConnection connection = new SqlConnection(cs))
{
string sql = "SELECT name FROM people WHERE name LIKE '" + prefixText + "%'";
SqlDataAdapter adapter = new SqlDataAdapter();
adapter.SelectCommand = new SqlCommand(sql, connection);
adapter.Fill(ds);
}
foreach (DataRow dr in ds.Tables[0].Rows)
{
items.Add(dr["name"].ToString());
}
return items.ToArray();
}
}