public List <StudentAssignment> getListOfAnswer(int lesson, string Username)
        {
            List <StudentAssignment> stlist = new List <StudentAssignment>();

            try
            {
                con.Open();
                SqlCommand    cmd = new SqlCommand("select QuestionNo,Answer,DatabaseName from StudentAssignment where LessonNo=" + lesson + "and UserName='******'", con);
                SqlDataReader sdr = cmd.ExecuteReader();
                while (sdr.Read())
                {
                    StudentAssignment up = new StudentAssignment();
                    up.QuestionNo = sdr["QuestionNo"].ToString();
                    up.Answer     = sdr["Answer"].ToString();

                    up.DatabaseName = sdr["DatabaseName"].ToString();
                    stlist.Add(up);
                }

                con.Close();
                return(stlist);
            }

            catch (Exception ex)
            {
                return(null);
            }
        }
        public string InsertAssignment(StudentAssignment sp)
        {
            try
            {
                con.Open();
                string q = "insert into StudentAssignment (UserName,AssignmentID,classID,DatabaseName,QuestionNo,Answer,LessonNo)" +
                           " values (@User,@assID, @ClassID,@DatabaseName,@QuestionNo,@Answer,@LessonNo)";
                SqlCommand cmd = new SqlCommand(q, con);
                cmd.Parameters.AddWithValue("@User", sp.UserName);
                cmd.Parameters.AddWithValue("@assID", sp.AssignmentID);
                cmd.Parameters.AddWithValue("@ClassID", sp.classID);
                cmd.Parameters.AddWithValue("@DatabaseName", sp.DatabaseName);
                cmd.Parameters.AddWithValue("@QuestionNo", sp.QuestionNo);
                cmd.Parameters.AddWithValue("@Answer", sp.Answer);
                cmd.Parameters.AddWithValue("@LessonNo", sp.LessonNo);



                cmd.ExecuteNonQuery();
                con.Close();


                return("SuccessFul");
            }catch (Exception ex)
            {
                return(ex.ToString());
            }
        }