I know this isn't possible in Postgres, and I suspect it is incompatible with SQL in general.

SQL has no problem with it, and neither does Postgres. However, the basic structure of most RDBMSes have issues with data that is versioned over time. I run into this all the time with data warehousing. The solution isn't an SQL solution - it's a database engine solution, but those aren't going to be easy to have done.

The best solution that I've thought up is to modify the InnoDB engine to do three things:

  1. shift from versioning rows using a version number to using a date
  2. keep all old copies of a row around
  3. add a MySQL-specific SQL extension to allow queries to access old versions of rows

I talked with Jeremy Zawodny back in June when I took his MySQL class and he said that, theoretically, it should work. But, he said that the issue was tuits and that it would come a lot faster if I had a few tuits to get it started. *shrugs*

Being right, does not endow the right to be rude; politeness costs nothing.
Being unknowing, is not the same as being stupid.
Expressing a contrary opinion, whether to the individual or the group, is more often a sign of deeper thought than of cantankerous belligerence.
Do not mistake your goals as the only goals; your opinion as the only opinion; your confidence as correctness. Saying you know better is not the same as explaining you know better.

In reply to Re^2: Conditional many to many relationships with Class::DBI by dragonchild
in thread Conditional many to many relationships with Class::DBI by BigLug

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