martind-crap1_at_mailblocks.com wrote:
> Thanks!
>
> I don't want to go the many-to-many route, as I want to maintain
> "delete-on-removal" logic (I'm using Hibernate for my persistence
> layer, and it will not delete unreferenced items from n-to-m, only
> 1-to-n)
>
> DA Morgan wrote:
>
>>martind-crap1_at_mailblocks.com wrote:
>>
>>>Hi,
>>>
>>>What is the best way to model this: Assume I have two objects: Agency
>>>and Publisher, and both have a 1-to-n relationship to Employee. This is
>>>a true 1-to-n relationship, as each Employee can only work for one
>>>Agency or one Publisher. Let's assume further that I cannot introduce a
>>>supertype (e.g. Employer) which holds the 1-to-n relationship.
>>>
>>>My preferrd solution is to have a foreign key in Emplyee that can
>>>either link to a primary key of Agency or Publisher (all my primary
>>>keys are 64-bit IDs that are unqiue across the database). However, now
>>>I won't be able to map a bi-directional association, without indicating
>>>in Employee whether this is an "Agency" or "Publisher" relationship
>>>(ala <ANY>).
>>>
>>>My other option is to use two tables, AgencyEmployee and
>>>PublisherEmployee, which can then be linked as traditional 1-to-n
>>>bidirectional associations.
>>>
>>>What do you guys consider best practice in this situation?
>>>
>>>Cheers,
>>>
>>>Jen
>>
>>Over a period of time an employee can be both even if at any specific
>>point-in-time only 1. I would model it as a many-to-many with an
>>intersecting entity and a unique constraint to make it impossible for
>>someone to simultaneously be both if such is the case.
>>
>>--
>>Daniel A. Morgan
>>http://www.psoug.org
>>damorgan_at_x.washington.edu
>>(replace x with u to respond)
- Please do not top post
- Hibernate is database ignorant. If working against an Oracle
database I'd suggest a different framework and that you that
data integrity belongs in the database ... not in your front-end
code.
And if you would like to engage me in a religious war with respect
to item #2, feel free, then give me 10 seconds with SQL*Plus to
demonstrate why your attempt to enforce data integrity doesn't work.
--
Daniel A. Morgan
http://www.psoug.org
damorgan_at_x.washington.edu
(replace x with u to respond)
Received on Mon May 30 2005 - 16:02:34 CDT
