use bidi;
insert into t values
   (1,   'abc',   1,  '2010-02-01 05:45:30'),  -- same
   (2,   'def',   2,  '2010-01-31 06:11:11'),
   (3,   'ghi',   5,  '2010-02-01 09:17:51'),  -- 1s older than master
   (4,   'jkl',   6,  '2010-02-01 10:11:33'),
   (5,   NULL,    0,  '2010-02-02 05:10:00'),  -- updated to NULL
   (6,   'p',     4,  '2010-01-31 10:17:00'),
   (7,   'qrs',   5,  '2010-02-01 10:11:11'),  -- same
   (8,   'tuv',   6,  '2010-01-31 10:17:20'),
   (9,   'wxy',   7,  '2010-02-01 10:17:00'),  -- same
   (10,  'z',     8,  '2010-01-31 10:17:08'),
   (11,  '?',     0,  '2010-01-29 11:17:12'),  -- new row
   (12,  '',      0,  '2010-02-01 11:17:00'),
   (13,  'hmm',   1,  '2010-02-02 12:17:31'),  -- newer date, exact time
   (14,  NULL,    0,  '2010-01-31 10:17:00'),
   (15,  'gtg',   7,  '2010-02-02 06:01:08'),  -- updated
   (17,  'good',  1,  '2010-02-02 21:38:03');  -- new row