Re: [SQLObject] Re: SQLObject

[Bud P. B. <bu...@si...>]

On Fri, 11 Apr 2003 08:23:51 -0500
Brad Bollenbach <br...@bb...> wrote:

> In either case, this will not affect anything in comments, because
> this is a table that would probably look like:
> 
> Comments
> comment_id
> comment_desc
> ...
> etc.

If this is your comments table, there are no problems.  However, the
problem I try to illustrate uses the following table:

CREATE TABLE ProjectWorkerComment(
  project_id INT,
  worker_id INT,
  comment_id INT,
  PRIMARY KEY (project_id, worker_id, comment_id),
  FOREIGN KEY (project_id, worker_id) REFERENCES ProjectWorker);

It may not be a realistic example, but I was attempting to quickly
think of something to add additional levels to the hierarchy of
composite foreign key relationships.  If you have such a hierachy,
changing relationships at a higher level (for business logic reasons)
implies that you change the composite keys of all related tables at
lower levels.  

--b