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Joe Celko's Thinking in Sets: Auxiliary, Temporal, and Virtual Tables in SQL by Joe Celko

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9.1. The Nature of Time

Time is not a simple thing. Most data processing is done with data that is discrete by its nature. An account number is or is not equal to a value. A measurement has a value to so many decimal places. But time is a continuum, which means that given any two values on the time line, you can find an infinite number of points between them. Then we have the problem of which kind of infinite. Most nonmath majors do not even know that some transfinite numbers are bigger than others!

Do not panic. For purposes of a database the rule we need to remember is that “Nothing happens instantaneously” in the real world. Einstein declared that duration in time is the fourth dimension that everything must have to exist. But before Einstein, ...

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