> > For example, imagine that you have a table of employees and a table of
> > departments that the employees work for. This would be a one to many and
> > possible many to many relationship. Now imagine that you also want to
> > capture the managers of each department. Each department can only have
one
> > manager and an employee can only be a manager of one department, so, you
> > would need a one to one relationship, called manages, between the
employee
> > and department table.
> >
> > How else would you model this? Both entities, employees and departments
are
> > completely different and thus you couldn't put them in the one table.
Maybe
> > the database books that I have been reading have been incorrect or has
> > database theory changed recently?
> >
> > 1 1
> > |employee| --- <manages> --- |department|
> >
>
> Not at all. 1:1 is often found in a logical model. One normalizes then,
where
> appropriate, denormalizes when creating the physical model.
>
> Same goes for M:M (many to many) relationships. They may exist in a
logical
> model but they absolutely do not belong in a physical model.
>
> Daniel Morgan
>
Ok then, then how could I change the above model so that it didn't have to
be a one to one and still have it make sense? Afterall, there can be only
one manager per department, but the manager should go in the employee table
where there could be many employees per department. I'm just curious as I
don't know how it could be changed to fit a physical model and still make
sense as implementing this another way may save me heaps of time and make
the databse heaps simpler.
Received on Tue Mar 18 2003 - 21:58:09 CST
