using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SqlClient;
using System.Linq;
using System.Web;
using System.Web.Script.Serialization;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace Jsonyap
{
    public partial class _Default : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            JavaScriptSerializer js = new JavaScriptSerializer();
            string query = String.Format("SELECT * FROM lecturer ORDER BY id;");
            try
            {
             /*   foreach (DataRow item in SorguCalistir(query).Tables["lecturers"].Rows)
                {
                    hoca h1 = new hoca();
                    h1.id = Convert.ToInt16(item["id"].ToString());
                    h1.Name = item["Name"].ToString();
                    h1.Rank = item["Rank"].ToString();
                    h1.Research = item["Researh"].ToString();
                    h1.Email = item["Email"].ToString();
                    h1.Office = item["Office"].ToString();
                    h1.PhoneNumber = item["PhoneNumber"].ToString();
                    string str = js.Serialize(h1);
                    Label1.Text = str;
                }*/

                SqlConnection con = new SqlConnection("Server=Gorkem;Database=hocalar;Trusted_Connection=True;");
                con.Open();
                SqlCommand sorgu = new SqlCommand();
                sorgu.Connection = con;
                sorgu.CommandText = query;
                SqlDataReader data = sorgu.ExecuteReader();
               
                while (data.Read())
                {
                    Hoca h1 = new Hoca();
                    Lecturer l1 = new Lecturer();
                    l1.id = Convert.ToInt16(data[0].ToString());
                    l1.Name = data[1].ToString();
                    l1.Rank = data[2].ToString();
                    l1.Research = data[3].ToString();
                    l1.Email = data[4].ToString();
                    l1.Office = data[5].ToString();
                    l1.PhoneNumber = data[6].ToString();
                    h1.lecturer.Add(l1);
                    string str = js.Serialize(h1);
                    Label1.Text += str;
                }
            }
            catch (Exception ex)
            {

                Label1.Text = ex.Message.ToString();
            }
           
        }

        public DataSet SorguCalistir(string query)
        {

            SqlConnection con = new SqlConnection("Server=Gorkem;Database=hocalar;Trusted_Connection=True;");
            con.Open();
            SqlDataAdapter da = new SqlDataAdapter(query, con);
            da.SelectCommand.ExecuteNonQuery();
            DataSet dt = new DataSet();
            da.Fill(dt);
            return dt;


        }

    }
}
public class Lecturer
{
    public int id { get; set; }
    public string Name { get; set; }
    public string Rank { get; set; }
    public string Research { get; set; }
    public string Email { get; set; }
    public string Office { get; set; }
    public string PhoneNumber { get; set; }
}


public class Hoca
{
    public List<Lecturer> lecturer { get; set; }
}
kırmızı ile belirttiğim alanda hata veriyor