SQL沉思录

CHAPTER9  TEMPORAL TABLES

1. internet time

   -- 1.beat = 86.4 seconds; 1 000 .beats = 24 hours = 1 day;

2. the iso Half-Open Interval Model:

   [t1,t3) + [t2,t4) = [t1,t4)    <!-- t1<t2<t3<t4 -->

   -- only 00:00:00 , no such time as 24:00:00;

   -- mysql allows the use of 2008-10-00 means the range of dates from 2008-10-01 to 2008-10-31;

       likewise, 2008-00-00 means the entire year 2008;

3.