[AccessD] Normalization discussion

Child table is one where an entry cannot exist without the parent entry

As in you can define the species in a table without specifying the animals in
the species
So Species would be the PARENT of animals because 
An animal has to be within a species, but a species can have several animals in
it

Delete (exterminate) a species and you lose lots of animals 
Delete (exterminate) an animal and you still have others of the same species

JimB

-----Original Message-----
From: accessd-bounces at databaseadvisors.com
[mailto:accessd-bounces at databaseadvisors.com] On Behalf Of Susan Harkins
Sent: Friday, August 29, 2014 4:39 PM
To: Access Developers discussion and problem solving
Subject: Re: [AccessD] Normalization discussion

Right now, most of my foreign keys in the parent table are simple lookups.
For instance, species -- each individual has a species and those are in a
child table. We'll update that table infrequently -- only if we add a new
species. We have several individuals of each species. Another is gender --
female and male, but the parent table has a foreign key to the gender
table. (Gender's probably overkill, but I'm on autopilot I think). I'm also
tracking acquisition method -- there are only three, so again, it's a
lookup table and not a true child table.

Susan H.








On Fri, Aug 29, 2014 at 10:18 AM, Charlotte Foust <charlotte.foust at gmail.com
> wrote:

> A foreign key is a key that points to the PK in another table.  You're
> mixing keys with parent child relationships, which are defined through
> keys.  In a data warehouse, you put a bunch of keys in the central table,
> but in a regular database you put the parent PK into the child tables so
> they know their mommy,  The idea is to put the keys where they are needed.
>
> Charlotte
>
>
> On Fri, Aug 29, 2014 at 6:07 AM, Susan Harkins <ssharkins at gmail.com>
> wrote:
>
> > I'll spend the morning rereading the book Martin and I wrote, brushing up
> > on the normalization part. I've forgotten a lot of the basics. I'm
> writing
> > an animal tracing database in Access and I'm trying to remember if it
> > matters where the fk goes. Now, I remember its purpose and all that, but
> it
> > would be so much simpler if I could just drop them all into the main
> table
> > instead of adding a fk to all the child tables to the main table -- I
> think
> > anyway.
> >
> > So, I've got a main table of animals and all of the remaining tables are
> > child tables of a sort and a few lookup tables. Is it reasonable to just
> > add a fk to all those child tables in my parent table?
> >
> > I just don't remember. I haven't built a database in... seriously... 10
> > years? It's been long enough that I'm really struggling.
> >
> > Susan H.
> > --
> > AccessD mailing list
> > AccessD at databaseadvisors.com
> > http://databaseadvisors.com/mailman/listinfo/accessd
> > Website: http://www.databaseadvisors.com
> >
> --
> AccessD mailing list
> AccessD at databaseadvisors.com
> http://databaseadvisors.com/mailman/listinfo/accessd
> Website: http://www.databaseadvisors.com
>
-- 
AccessD mailing list
AccessD at databaseadvisors.com
http://databaseadvisors.com/mailman/listinfo/accessd
Website: http://www.databaseadvisors.com