--- Douglas Sims <[EMAIL PROTECTED]> wrote:
>
> Does anyone know of a thorough discussion of effective dating on the
>
> web, particularly with respect to MySQL, or have any opinions you
> could share?
>
> I've worked with effective-dated tables in MS SQL Server and never
> been particularly awe-struck by how well it works. I can think of
> three ways of doing it:
>
> 1) Store a "Begin" date and an "End" date for each row and then
> reference the row with 'WHERE {transaction date} BETWEEN {begin} AND
>
> END. This inevitably winds up with overlapping rows that shouldn't
> be or gaps where you don't want them, and also requires an extra date
>
> column, but the select queries are simplest. Also, what about
> indexing the dates?
>
> 2) Store an "Expires" date with each row, but then to find the actual
>
> row you have to do a subselect or some messy joins and I'm not at all
>
> confident this will be optimized reasonably.
>
> 3) Store an "Effective as of" date with each row but this has
> essentially the same problem as 2.
>
> None of the SQL books on my shelf even mentions this, including
> Jeremy Zawodny's "Hi-Performance MySQL" and the "MySQL Reference
> Manual."
>
> This page is interesting but doesn't explain the different options
> nor try to analyze which is best and under what circumstances:
> http://
> llamasery.com/forums/showthread.php?p=34945
>
> Strangely enough, most of what I find by googling the topic
> "effective dating" has to do with meeting girls efficiently - which
> is also interesting, but outside the scope of this list and not
> immediately relevant to the system I'm working on.
>
>
> Douglas Sims
> [EMAIL PROTECTED]
>
>
I have also heard of this style of design called "chonological
database". Doing this Google returned some more relevant information:
http://www.google.com/search?num=100&hl=en&lr=&q=chronological+effective+date+%2Bdatabase&btnG=Search
Shawn Green
Database Administrator
Unimin Corporation - Spruce Pine
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