public List <DBOpenAnswer> getByKeys(List <int> keys)
        {
            List <DBOpenAnswer> result  = new List <DBOpenAnswer>();
            DBManager           manager = new DBManager(true);

            String sqlCommand = "Select * From dbo.OpenAnswers answer Where ";

            for (int i = 0; i < keys.Count; i++)
            {
                if (i != keys.Count - 1)
                {
                    sqlCommand += "answer.question_id = " + keys[i] + " OR ";
                }
                else
                {
                    sqlCommand += "answer.question_id = " + keys[i] + ";";
                }
            }
            var reader = manager.Read(sqlCommand);

            while (reader.Read())
            {
                DBOpenAnswer answer = new DBOpenAnswer();
                answer.Question_id = (int)reader["question_id"];
                answer.User_id     = (String)reader["user_id"];
                answer.Probability = (float)reader["probability"];

                result.Add(answer);
            }



            manager.Close();
            return(result);
        }
        public DBOpenAnswer getByKey(int answer_id)
        {
            String    sqlCommand = "Select * From dbo.OpenAnswers answer Where answer.question_id = " + answer_id + ";";
            DBManager manager    = new DBManager(true);
            var       reader     = manager.Read(sqlCommand);

            if (!reader.Read())
            {
                return(null);
            }

            DBOpenAnswer answer = new DBOpenAnswer();

            answer.Question_id = (int)reader["question_id"];
            answer.User_id     = (String)reader["user_id"];
            answer.Probability = (float)reader["probability"];

            manager.Close();

            return(answer);
        }