                   time id  num 0  0000-00-00 00:00:00  A    0 0  0000-00-00 00:00:00  A    0 0  0000-00-00 00:00:00  B   00 0  0000-00-00 00:00:00  B   00 0  0000-00-00 00:00:00  B   00 0  0000-00-00 00:00:00  B   00 00 0000-00-00 00:00:00  C  000 00 0000-00-00 00:00:00  C  000 00 0000-00-00 00:00:00  C  000 00 0000-00-00 00:00:00  C  000 