Chris,
> ..or generally: how do you create two crosslinked foreign keyed tables?
>
> hopefully an easy problem for the real professionals!
No. The problem is: Why would you want to create two crosslinked
foriegn-keyed tables? As an experienced SQL professional, this seems
like a recipe for instant disaster to me.
The purpose of a foriegn key is to enforce a parent-->child or data
table<--reference list relationships, to prevent incomplete or erroneous
records from being added. This requires the foriegn key relationship to
be one-way.
In fact, if you built your two-way foriegn keys (using ALTER TABLE), I
think you might find that you can't add any records to either table.
Certainly you won't be able to delete any. I once had an experience
with a complex legacy data structure where I accidentally set up a
circular foriegn key relationship (among 5 tables), and I had to
re-build the database from scripts to fix it.
If you're looking to set up a many-to-many relationship, then what you
want is a linking table. However, I highly advise you to pick up a
primer on database design (such as "Database Design for Mere Mortals")
before proceeding any further, or you'll end up spending the next year
paying for what you don't understand now.
-Josh Berkus
--
______AGLIO DATABASE SOLUTIONS___________________________ Josh Berkus Complete
informationtechnology josh@agliodbs.com and data management solutions (415) 565-7293 for law firms, small
businesses fax 621-2533 and non-profit organizations. San Francisco
