Facebook type search box with auto complete using jquery, ajax and C#

search.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.Services;
using System.Data;

public partial class _Default : System.Web.UI.Page
{
    protected void Submit(object sender, EventArgs e)
    {      
        lblParticular.Text = Request.Form[txtSearch.UniqueID].ToString();
        lblStockId.Text = Request.Form[hfStockId.UniqueID].ToString();
    }

    [WebMethod]
    public static string getItem(string Search, string StockId)
    {
        string Item="";
        bl_M_StockCreation obj = new bl_M_StockCreation();
        string[] itemArr = StockId.Split('_');
        DataSet dsStock = obj.getItem(Search, itemArr[0]);
        if (dsStock.Tables[0].Rows.Count != 0)
        {
            dsStock.Tables[0].TableName = "StockDetails";
            Item = dsStock.GetXml();
        }
       
        return Item;
    }
}

Service.asmx

using System;
using System.Collections.Generic;
using System.Web;
using System.Web.Services;
using System.Data.SqlClient;
using System.Configuration;
using System.Web.Script.Services;
using System.Data;

/// <summary>
/// Summary description for Service_CS
/// </summary>
[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
// To allow this Web Service to be called from script, using ASP.NET AJAX, uncomment the following line.
[System.Web.Script.Services.ScriptService]
public class Service : System.Web.Services.WebService {

    public Service () {
    }

    [WebMethod]
    [ScriptMethod(ResponseFormat = ResponseFormat.Json)]
    public string[] GetParticular(string prefix)
    {
        List<string> Particulars = new List<string>();
        using (SqlConnection conn = new SqlConnection())
        {
            conn.ConnectionString = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;

            using (SqlCommand cmd = new SqlCommand("[USP_M_Test]"))
            {
                cmd.CommandType = CommandType.StoredProcedure;
                cmd.Parameters.AddWithValue("@Search", prefix);
                cmd.Parameters.AddWithValue("@intMode", 1);
                cmd.Connection = conn;
                conn.Open();
                using (SqlDataReader sdr = cmd.ExecuteReader())
                {
                    while (sdr.Read())
                    {
                        Particulars.Add(string.Format("{0}-{1}", sdr["Particulars"], sdr["StockId"]));
                    }
                }
                conn.Close();
            }
            return Particulars.ToArray();
        }
    }




}