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Old January 7th, 2010, 09:56 PM posted to microsoft.public.access.tablesdbdesign
Pamela
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Posts: 193
Default Lookup fields referring to tbls w/o relationship

Hi Jeff,

In my research, I understand that it is always best to have items in a table
relate to 1 topic only. In the case of our business, we inspect cars that
have been in an accident for the insurance companies. In the case of this
db, the only purpose it was originally to serve was to take info about the
inspection and concatenate it into a paragraph complete with our legal
verbage, disclaimers etc., which we then have to paste into the insurance
company's online system.

With this in mind, I broke the tables down into these: tblClaim,
tblInspection (date of, etc) , tblLocation (where it took place), tblDamage
(classifying the damage, the measurements of, etc) and tblEstimate. For this
purpose, I felt a one-to-one was best. Each claim has 1 inspection, 1
location, 1 set of damage info, 1 estimate, etc all joined around our central
assignment # which is the PK on all of the tbls and which I use for the
relationships. I have other tables that I use to populate my cbos and those
are really from where my question stems. I have tblInsuranceCompany which
populates cboInsuranceCompany but there is no direct relationship that I
needed to make for it to work and work well, as I stated before. Is it
sufficient to leave it as it is or if I decide to expand upon my db will I
run into issues because it doesn't have a direct relationship established?
Thanks so much!
Pamela

"Jeff Boyce" wrote:

Pamela

Access is a relational database. It is optimized to work with
well-normalized data.

It is somewhat rare to have a number of tables related one-to-one in a
well-normalized relational database. That usually only happens when you
have "sub-typing". For example, you could have a list of equipment at your
work, but of different types, each with different characteristics (e.g.,
Computers, Desks, Chairs, Bookcases, ...). You might decide to create one
table to "inventory" them all, giving each a unique inventoryID, but use
separate tables to hold the particulars on each different class/type of
equipment (i.e., chairs don't have the same characteristics that computers
do). That's a one-to-one situation.

The only one who knows if the things about which you are collecting data are
related is you. Access can't tell that. We can't help with that unless you
describe your situation a bit more.

More info, please...

Regards

Jeff Boyce
Microsoft Access MVP

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Disclaimer: This author may have received products and services mentioned
in this post. Mention and/or description of a product or service herein
does not constitute endorsement thereof.

Any code or pseudocode included in this post is offered "as is", with no
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You can thank the FTC of the USA for making this disclaimer
possible/necessary.

"Pamela" wrote in message
...
I created a db and in reading now about db structure, I've seen a lot of
mention of relationships. My db started out very simple with the tables
that
I used for relationships all being one-to-one and now I'm considering
adding
to it. In it, however, I also have some tables that I used (not w/ the
Lookup Wizard but on my own) simply as lookup - populating cbos. I didn't
seem to need to set relationships with these though for it to work and
work
well. Why didn't it require a relationship and what are the pros & cons
of
setting them up this way vs. w/ a relationship?
Thanks so much for your help!
Pamela



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