public static HashSet<UserQuestionState> getUserQuestionStateRows() {
        Connection conn = ConnectionManager.getInstance().getConnection();
        
        String sql = "{call selectUserQuestionStateRows()}";

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

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

            while (rs.next()) {
                UserQuestionState userQuestionStateEntity = new UserQuestionState();
                userQuestionStateEntity.setUserNo(rs.getString("userNo"));
                userQuestionStateEntity.setQuestionNo(rs
                        .getString("questionNo"));
                userQuestionStateEntity.setHasCompleted(rs
                        .getBoolean("hasCompleted"));

                hashSet.add(userQuestionStateEntity);
            }
            return hashSet;

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