public void showTable(String tableName)  {
    logArea.append( "Start show table: " +tableName+ "\n" );
    try {
      Statement stmt = conn.createStatement();
      ResultSet rs = stmt.executeQuery( "SELECT gr_id FROM " +tableName);
      while (rs.next()){
        String grId = rs.getString( "1 ");
        System.out.println(grId);
//        String grName = rs.getString( "1 ");
//        String grDescr = rs.getString( "2 ");
//        System.out.println( "Id: " +grId+ "; Name: " +grName+ "; Description: " +grDescr);
      }
    }
    catch (Exception ex) {
        logArea.append( "Error in showTable: \n" +ex.toString());
    }
  }