试图从sql获取数据到文本框。位置0异常没有行

 public void doldur()
    {
        SqlConnection con = new SqlConnection(@"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=|DataDirectory|\Odev.mdf;Integrated Security=True");
        con.Open();

        SqlDataAdapter da = new SqlDataAdapter("Select * From ogrenciler Order By adsoyad ASC", con);
        DataSet dts = new DataSet();

        da.Fill(dts, "ogrenciler");
        comboBox1.DataSource = dts.Tables["ogrenciler"];
        comboBox1.ValueMember = "adsoyad";
        comboBox1.DisplayMember = "adsoyad";

        comboBox2.DataSource = dts.Tables["ogrenciler"];
        comboBox2.ValueMember = "adsoyad";
        comboBox2.DisplayMember = "adsoyad";

        con.Close();
    }
 public void doldur()
    {
        SqlConnecti