ช่วยดูโค้ดให้ผมหน่อยครับ วนลูปเก็บค่าลง DataTable แล้วเอาข้อมูลไปโชว์ใน Gridview แล้วมันโชว์ค่าสุดท้ายค่าเดียว

var qs6 = from p in db.Students
                              where p.SubjectID == txtSubID.Text.Trim() && p.Section == txtSec.Text.Trim()
                              select p.StudentID;

                    var student = from s in db.StudentTimeTables
                                  where s.DateExam == txtDateExam.Text.Trim()
                                  select s.StudentID;
                    foreach (var c in qs6)
                    {
                        foreach (var d in student)
                        {
                            if (Convert.ToInt32(c) == Convert.ToInt32(d))
                            {
                                var qs8 = from q in db.StudentTimeTables
                                          where q.StudentID == d && txtDateExam.Text.Trim() == q.DateExam
                                          select new { q.timeStart, q.timeStop };
                                foreach (var q in qs8)
                                {
                                    if (Convert.ToDouble(txtTimeStart.Text.Trim()) <= Convert.ToDouble(q.timeStart) && Convert.ToDouble(txtTimeStop.Text.Trim()) > Convert.ToDouble(q.timeStart) && Convert.ToDouble(txtTimeStop.Text.Trim()) <= Convert.ToDouble(q.timeStop)
                                        || Convert.ToDouble(txtTimeStart.Text.Trim()) > Convert.ToDouble(q.timeStart) && Convert.ToDouble(txtTimeStart.Text.Trim()) < Convert.ToDouble(q.timeStop) && Convert.ToDouble(txtTimeStop.Text.Trim()) <= Convert.ToDouble(q.timeStop)
                                        || Convert.ToDouble(txtTimeStart.Text.Trim()) > Convert.ToDouble(q.timeStart) && Convert.ToDouble(txtTimeStart.Text.Trim()) < Convert.ToDouble(q.timeStop) && Convert.ToDouble(txtTimeStop.Text.Trim()) > Convert.ToDouble(q.timeStop)
                                        || Convert.ToDouble(txtTimeStart.Text.Trim()) <= Convert.ToDouble(q.timeStart) && Convert.ToDouble(txtTimeStop.Text.Trim()) >= Convert.ToDouble(q.timeStop))
                                    {
                                        
                                        DataTable dt = new DataTable();
                                        GridView2.DataSource = dt;
                                        dt.Columns.Add(new DataColumn("id"));
                                        DataRow dr = dt.NewRow();
                                        dr["id"] = d;
                                        dt.Rows.Add(dr);

                                    }                                 
                                }                                
                            }                   
                        }                        
                    }
                    lblCheck.Visible = true;
                    lblCheck.Text = "มีนิสิตที่ไม่สามารถลงได้ในเวลานี้";
                    GridView2.Visible = true;
                    //GridView2.DataSource = 
                    GridView2.DataBind();