public List <MarksRecords> SearchByID(string ID)
        {
            List <MarksRecords> MarksList = new List <MarksRecords>();

            int i, length;

            SqlConnection con = new SqlConnection(@"Data Source=(localdb)\MSSQLLocalDB;Initial Catalog=MarksManagementDB;Integrated Security=True;Connect Timeout=30;Encrypt=False;TrustServerCertificate=False;ApplicationIntent=ReadWrite;MultiSubnetFailover=False");
            SqlCommand    cmd = new SqlCommand();

            cmd.Connection = con;

            cmd.CommandText = "select * from MarksRecords where UserID = @uid";
            cmd.Parameters.AddWithValue("@uid", ID);

            SqlDataAdapter da = new SqlDataAdapter(cmd);
            DataSet        ds = new DataSet();

            con.Open();

            da.Fill(ds, "MarksRecords");
            DataTable dt = ds.Tables["MarksRecords"];

            length = ds.Tables["MarksRecords"].Rows.Count;

            if (length == 0)
            {
                return(null);
            }

            for (i = 0; i < length; i++)
            {
                MarksRecords m = new MarksRecords();
                m.UserID   = ds.Tables["MarksRecords"].Rows[i][0].ToString();
                m.Semester = (int)ds.Tables["MarksRecords"].Rows[i][1];
                m.Subject1 = (int)ds.Tables["MarksRecords"].Rows[i][2];
                m.Subject2 = (int)ds.Tables["MarksRecords"].Rows[i][3];
                m.Subject3 = (int)ds.Tables["MarksRecords"].Rows[i][4];
                MarksList.Add(m);
            }

            return(MarksList);
        }
        public string AddMarks(MarksRecords marks)
        {
            SqlConnection con = new SqlConnection(@"Data Source=(localdb)\MSSQLLocalDB;Initial Catalog=MarksManagementDB;Integrated Security=True;Connect Timeout=30;Encrypt=False;TrustServerCertificate=False;ApplicationIntent=ReadWrite;MultiSubnetFailover=False");
            SqlCommand    cmd = new SqlCommand();

            cmd.Connection  = con;
            cmd.CommandText = "select * from MarksRecords where UserID = @uid1 and Semester = @sem1";
            cmd.Parameters.AddWithValue("@uid1", marks.UserID);
            cmd.Parameters.AddWithValue("@sem1", marks.Semester);
            con.Open();
            SqlDataReader reader = cmd.ExecuteReader();

            if (reader.HasRows)
            {
                reader.Close();
                con.Close();
                return(null);
            }
            else
            {
                reader.Close();
                cmd.CommandText = "insert into MarksRecords(UserID,Semester,Subject1,Subject2,Subject3) values (@uid,@sem,@s1,@s2,@s3)";
                cmd.Parameters.AddWithValue("@uid", marks.UserID);
                cmd.Parameters.AddWithValue("@sem", marks.Semester);
                cmd.Parameters.AddWithValue("@s1", marks.Subject1);
                cmd.Parameters.AddWithValue("@s2", marks.Subject2);
                cmd.Parameters.AddWithValue("@s3", marks.Subject3);
                float  per    = (float)(marks.Subject1 + marks.Subject2 + marks.Subject3) / 3;
                string result = null;
                if (per < 35)
                {
                    result = "FAIL";
                }
                else
                {
                    result = "PASS";
                }
                cmd.ExecuteNonQuery();
                con.Close();
                return(result);
            }
        }