RE: Need ideas for SQL join select to replace logical view

["Joe Pluta" <joepluta@xxxxxxxxxxxxxxxxx>]

> From: Wilt, Charles
>
> Joe,
>
> As I consider it, it seems to me that the owner end timestamp really isn't
> derived from the start of the next owner timestamp.

They were in your own words, where you said you would add one millisecond to
the previous end to get the start.  Same with the other suggestion, where a
trigger program was forcing the start to the end of the previous.


> Consider the question:
> Who owned the car from 2/5/06@4:01 to 2/6/06@11:09?
>
> I believe the derived answer would be Bill.  But I think the correct
> answer is nobody, given the original data.

This will be my last post, I think, since we're veering off the original
question into the design of the application.  You are now rewriting the
business requirements.  You are assuming that Bill trading in the car
absolves him of ownership of subsequent events.  You have no reason to do
that based on the original post, only based on your own reading of the
situation.

Note that I'm not saying it's not true, simply that you're using facts not
in evidence to try and prove your point, which is bad logic.


> However, if the OWNER table was chronologically complete as Chuck
> suggested, then I agree with you that owner end timestamp would be
> derivable.

And that's what Bill said as well.  I was addressing the actual situation.


> With a non-complete OWNER table, you've got to get the owner end time from
> someplace else.
>
> As I see it, there's two options.
> 1) If the ownership period is separate from anything else, then you need
> to store start & end.
> 2) If for instance, a particular transaction indicates start & end, then
> you can derive both from the
> transaction table.

If there really were situations where there was a "NONE" owner (or a STORE
owner as previously suggested), it would be simple to do by just writing a
*NONE owner record out when the car is traded in (or when any other event
occurs that causes transfer of responsibility occurs).

Simple, clean, done.

Joe