protected final Set<String> getList(String table, String column) throws DataLoadFailedException {
        Connection conn = getConnection();
        PreparedStatement statement = null;
        ResultSet set = null;
        try {
            statement = conn.prepareStatement("SELECT ? FROM ?");
            statement.setString(1, column);
            statement.setString(2, table);
            set = statement.executeQuery();
            Set<String> nameSet = new HashSet<String>();
            while (set.next()) {
                nameSet.add(set.getString(1));
            }
            return nameSet;
        } catch (SQLException ex) {
            throw new DataLoadFailedException(ex);
        } finally {
            if (set != null) {
                try {
                    set.close();
                } catch (SQLException ex) {
                }
            }
            if (statement != null) {
                try {
                    statement.close();
                } catch (SQLException ex) {
                }
            }
        }
    }