public static HashSet<ExerciseParameter> getExerciseParameterRows() {
        Connection conn = ConnectionManager.getInstance().getConnection();
        
        String sql = "{call selectExerciseParameterRows()}";

        try (PreparedStatement stmt = conn.prepareStatement(sql);
                ResultSet rs = stmt.executeQuery();) {

            HashSet<ExerciseParameter> hashSet = new HashSet<ExerciseParameter>();

            while (rs.next()) {
                ExerciseParameter exerciseParameterEntity = new ExerciseParameter();
                exerciseParameterEntity.setExerciseParameterNo(rs
                        .getString("exerciseParameterNo"));
                exerciseParameterEntity.setIsTest(rs.getBoolean("isTest"));
                exerciseParameterEntity.setIsLocked(rs.getBoolean("isLocked"));
                exerciseParameterEntity.setAccessBegin(rs
                        .getTimestamp("accessBegin"));
                exerciseParameterEntity.setAccessEnd(rs.getTimestamp("accessEnd"));
                exerciseParameterEntity.setTimeLimit(rs.getInt("timeLimit"));

                hashSet.add(exerciseParameterEntity);
            }
            return hashSet;

        } catch (SQLTransientConnectionException SQLtce) {
            return getExerciseParameterRows();
        } catch (SQLTransientException SQLte) {
            return getExerciseParameterRows();
        } catch (SQLException e) {
            System.err.println(e);
            return null;
        } finally {
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }