Re: Time and Data Question

bgsmith01_at_fs.fed.us wrote:
>
> Many times of data evolve through time, e.g. the list of employees in the
> company. Data such as those in an employees table have an explicit time
> domain attached to them; they were hired on a specific date and are still
> employed by the company or left on a specific date.
>
> My question is: Is there a general structure that is recommended for these
> types of data so that we can easily ask questions such as "who are the
> current employees" or "who were the employees on 5 Jan 1993"?
>

You need "Developing Time-Oriented Database Applications in SQL" by Richard Snodgrass, Morgan Kaufmann, 2000, ISBN 1-55860-436-7.

It covers this, and all sorts of similar issues.

-- 
Yours,
Jonathan Leffler (Jonathan.Leffler_at_Informix.com) #include <disclaimer.h>
Guardian of DBD::Informix v1.00.PC1 -- http://www.perl.com/CPAN
     "I don't suffer from insanity; I enjoy every minute of it!"