Question

Can you guys show me how to get this ERD in 5th normal form? We did a class assignment yesterday where we had a real client come in and explain to us his need my group came up with this model I am trying to take it a step further and see if I can get it to 5th normal form so that I can understand it better as next week we will be doing another group ERD that will have to be in 5nf the thing is I don’t know where to start and the book is not getting through to me. can you guys help me.Erd Model http://img534.imageshack.us/img534/2118/capturekk.jpg

New information "Fake Clients Needs"

The client has 2 departments "Lab 1,
Lab 2" that order medical items from
him, like gloves and pi pets etc..
the departments have grown and he
wants to keep track of what is in
inventory what the vendors are selling
who has the best price and what cost
center it came from.

The way he
explained it the item is ordered is that
an individual goes to him and asks for
supplies he then writes down what lab
the person is from the persons name
and what cost center to bill. but he
also wants to track what has been
purchased by date and what is in stock
and what has to be bought. He also
gave an example that some users want
items from a specific vendor that
might not have the best prices and he
also receives some catalogs in the
mails with prices too that he wants to
track.

I apologize if its jumbled but this is all from memory.

Answer 1

I’m going to stick my neck out and say your current schema doesn’t really have any eligibility for 5NF. Taking a quote from wikipedia, it says most 4NF tables already conform to 5NF:

Usage Only in rare situations does a
4NF table not conform to 5NF. These
are situations in which a complex
real-world constraint governing the
valid combinations of attribute values
in the 4NF table is not implicit in
the structure of that table. If such a
table is not normalized to 5NF, the
burden of maintaining the logical
consistency of the data within the
table must be carried partly by the
application responsible for
insertions, deletions, and updates to
it; and there is a heightened risk
that the data within the table will
become inconsistent. In contrast, the
5NF design excludes the possibility of
such inconsistencies.

http://en.wikipedia.org/wiki/Fifth_normal_form

Perhaps the purpose is not to make your database 5NF, but to understand it’s structure compared to 5NF and make an argument for why it might already be in 5NF.

Update: reading some form of consensus from the comments, it seems your design may already be in 5NF, whether it was by design or by accident from a previous normalization pass.