Web service สำหรับการค้นหา ในฐานข้อมูล ใช้ C# Web service สำหรับการค้นหา ในฐานข้อมูล ทำยังไงครับ

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Services;

using System.Data;
using System.Data.SqlClient;
using System.Web.Configuration;

/// <summary>
/// Summary description for AutoComplete
/// </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 AutoComplete : System.Web.Services.WebService 
{
    private SqlConnection sqlConnection;

    public AutoComplete () 
    {

        //Uncomment the following line if using designed components 
        //InitializeComponent(); 
        string sqlConnectionString = WebConfigurationManager.ConnectionStrings["SqlConnectionString"].ToString();
        sqlConnection = new SqlConnection(sqlConnectionString);
    }

    [WebMethod]
    public string HelloWorld() {
        return "Hello World";
    }

    [WebMethod]
    public DataTable ProvinceTable()
    {
        DataTable Dt = new DataTable();

        string sqlCommandString = "SELECT [ProvinceID], [ProvinceName] FROM [ProvinceTable]";
        SqlCommand sqlCommand = new SqlCommand(sqlCommandString, sqlConnection);

        try
        {
            SqlDataAdapter sqlAdapter = new SqlDataAdapter();
            sqlAdapter.SelectCommand = sqlCommand;
            sqlAdapter.Fill(Dt);
        }
        catch (Exception ex)
        {
            Dt = AddErrorMessage(ex.Message).Copy();
        }

        return Dt;
    }

    [WebMethod]
    public DataTable DistrictTable(int ProvinceID)
    {
        DataTable Dt = new DataTable();

        string sqlCommandString = "SELECT [ProvinceID], [DistrictID], [DistrictName] FROM [DistrictTable] WHERE [ProvinceID]=@ProvinceID";
        SqlCommand sqlCommand = new SqlCommand(sqlCommandString, sqlConnection);
        sqlCommand.Parameters.AddWithValue("@ProvinceID", ProvinceID);

        try
        {
            SqlDataAdapter sqlAdapter = new SqlDataAdapter();
            sqlAdapter.SelectCommand = sqlCommand;
            sqlAdapter.Fill(Dt);
        }
        catch (Exception ex)
        {
            Dt = AddErrorMessage(ex.Message).Copy();
        }

        return Dt;
    }

    [WebMethod]
    public DataTable SubDistrictTable(int DistrictID)
    {
        DataTable Dt = new DataTable();

        string sqlCommandString = "SELECT [DistrictID], [SubDistrictID], [SubDistrictName] FROM [SubDistrictTable] WHERE [DistrictID]=@DistrictID";
        SqlCommand sqlCommand = new SqlCommand(sqlCommandString, sqlConnection);
        sqlCommand.Parameters.AddWithValue("@DistrictID", DistrictID);

        try
        {
            SqlDataAdapter sqlAdapter = new SqlDataAdapter();
            sqlAdapter.SelectCommand = sqlCommand;
            sqlAdapter.Fill(Dt);
        }
        catch (Exception ex)
        {
            Dt = AddErrorMessage(ex.Message).Copy();
        }

        return Dt;
    }

    private DataTable AddErrorMessage(string ErrorMessage)
    { 
        DataTable Dt = new DataTable();

        Dt.Columns.Add(new DataColumn("ErrorMessage", System.Type.GetType("System.string"));

        DataRow Dr = Dt.NewRow();
        Dr["ErrorMessage"] = ErrorMessage;
        Dt.Rows.Add(Dr);

        return Dt;
    }
}