Retrieve (Get) data from Database using Web Mehthod in asp.net

Retrieve (Get) data from Database using Web Mehthod in asp.net 

pagename.aspx 
pagename.aspx.cs


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

public partial class Multiplefileuploader : System.Web.UI.Page
{

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
        {
            Getselect_tbl();
        }
    }
    protected void UploadMultipleFiles(object sender, EventArgs e)
    {

    }
    [WebMethod]
    public static List Getselect_tbl()
    {
        AdminLogin objAdminLogin = new AdminLogin();
        DataTable objdt = new DataTable();
        objdt = GetSelect("select AdminID,UserName,Password,LoginIP from tbl_Adminlogin");
        List list = new List();
      

        for (int i = 0; i < objdt.Rows.Count; i++)
        {
            AdminLogin admin = new AdminLogin();
            admin.AdminID = Convert.ToInt32(objdt.Rows[i]["AdminID"]);
            admin.UserName = Convert.ToString(objdt.Rows[i]["UserName"]);
            admin.Password = Convert.ToString(objdt.Rows[i]["Password"]);
            admin.LoginIP = Convert.ToString(objdt.Rows[i]["LoginIP"]);
            list.Add(admin);
        }
        return list;
    }
    [WebMethod]
    public static DataTable GetSelect(string query)
    {
        SqlConnection objSqlConnection = new SqlConnection("Data Source=sumitshekhawat; Initial Catalog = db_sumit; User ID=sa; password=user@123");
        SqlDataAdapter objadp = new SqlDataAdapter(query, objSqlConnection);
        DataTable dt = new DataTable();
        objadp.Fill(dt);
        return dt;
    }
}

public class AdminLogin
{
    private int adminID;
    private string userName;
    private string password;
    private string loginIP;

    public int AdminID
    {
        get { return adminID; }
        set { adminID = value;}
    }
    public string UserName
    {
        get { return userName; }
        set { userName = value; }
    }
    public string Password
    {
        get { return password; }
        set { password = value; }
    }
    public string LoginIP
    {
        get { return loginIP; }
        set { loginIP = value; }
    }
} 


 function.js


$(document).ready(function () {
    var type = "
Admin ID
User Name
Password
Login IP
";
    $.ajax({
        type: "post",
        url: "Multiplefileuploader.aspx/Getselect_tbl",
        data: "{}",
        contentType: "application/json; charset=utf-8",
        dataType: "json",
        success: function (data) {
            for (var i = 0; i < data.d.length; i++) {
                type += " " + data.d[i].AdminID + "
" + data.d[i].UserName + "
" + data.d[i].Password + "
" + data.d[i].LoginIP + "
";  
            }
            type += "";
            $("#tbl").append(type);
        },
        error: function (result) {
            alert("Error");
        },
        complete: function (result) {
        }
    })
})