text: create class test_class (date_col date, time_col time, timestamp_col timestamp, datetime_col datetime, datetime_col1 datetime);
  
  insert into test_class values (DATE '01/01/1971', TIME '09:00:00', TIMESTAMP '01/01/1972 10:30:00', DATETIME '1970-01-01 00:00:00.000', DATETIME '1970-01-01 00:00:00.000');
  insert into test_class values (DATE '01/02/2009', TIME '19:10:00', TIMESTAMP '01/11/2009 10:31:00', DATETIME '2008-01-12 08:08:08.999', DATETIME '2008-02-12 08:08:08.999');
  insert into test_class values (DATE '01/02/2009', TIME '19:10:00', TIMESTAMP '01/11/2009 10:31:00', DATETIME '2008-03-12 08:08:08.999', DATETIME '2008-01-12 08:08:08.999');
  
  select * from test_class where datetime_col = 0;
  select * from test_class where datetime_col <> 0;
  select * from test_class where datetime_col > 0;
  select * from test_class where datetime_col < 0;
  select * from test_class where datetime_col >= 0;
  select * from test_class where datetime_col <= 0;
  
  drop class test_class;