public int RunOracleTransaction(Student s, Marks[] m, Course[] c) {
  //TODO: validate s, m, c

  using (OracleConnection connection = new OracleConnection(connectionString)) {
    connection.Open();

    using (OracleCommand command = connection.CreateCommand()) {
      using (OracleTransaction transaction = connection.BeginTransaction(IsolationLevel.ReadCommitted)) {
        command.Transaction = transaction;

        try {
          // Insert the student
          //TODO: put actual query here 
          command.CommandText = 
            @"insert into Students(name)
                   values (:prm_Name)
                returning id into :prm_id"; // <- we want inserted student's id

          //TODO: check actual RDBMS types 
          command.Parameters.Add(":prm_Name", OracleType.VarChar).Value = s.Name;
          command.Parameters.Add(":prm_Id", OracleType.VarChar).Direction = ParameterDirection.Output;

          command.ExecuteNonQuery(); 

          string studentId = Convert.ToString(comm.Parameters[":prm_Id"].Value);

          // Insert his/her marks
          command.Parameters.Clear(); // <- forget all prior parameters

          //TODO: put actual query here 
          command.CommandText = 
            @"insert into StudentsMarks(student_Id, mark)
                   values (:prm_Student_Id, :prm_Mark)";

          //TODO: check actual RDBMS types 
          command.Parameters.Add(":prm_Student_Id", OracleType.VarChar).Value = studentId;
          command.Parameters.Add(":prm_Mark", OracleType.Int32);

          // insert each mark (in a loop)
          foreach (var mark in m) {
            command.Parameters[":prm_Mark"].Value = m.Mark;
            command.ExecuteNonQuery();  
          }

          // Finally, commit all the inserts
          transaction.Commit();
        }
        catch (DataException e) {
          transaction.Rollback();

          Console.WriteLine(e.ToString());
          Console.WriteLine("Neither record was written to database.");
        }
      }
    } 
  }

  //TODO: your method returns integer value, please return it  
}