On Thu, 2009-10-29 at 09:37 +0000, Richard Huxton wrote:
> There are cases where one time is genuinely unknown, and there we need
> a null.
The semantics of a period with one side NULL require a more clear
definition. I don't personally see a lot of utility in trying to support
NULL semantics, but if we want to support it, it needs to be clearly
defined.
Does TSQL-2 offer any guidance here?
> That's assuming we've got a guarantee
> that from<=to for all periods.
Of course. Except that means that a NULL on one side of a period is a
little less unknown than other kinds of NULLs ;)
Regards,Jeff Davis