Re: normalisation

The following response infers a lot from the schema you have posted. If you could post the

question (or the objective) then the numer of asumptions needing to be made would be

reduced.

The following appear to be anomolies:
In the orders table ProductTypeID, CreditNo, SiteID, do not appear dependent upon

(functionally determined by) OrderNum.

The following (where the first attribute is the primary key) may be an alternative design:

Supplier (SupplierID, Other Supplier Attributes) Purchases (PurchaseID, SupplierID, ProductID, DateOfPurchase, Other Purchase Attribtes)
Products (ProductID, Other Product Attributes) Sales (SaleID, CustomerID, ProductID, DateOfSale, Other Sale Attributes) Customer (CustomerID, Other Customer Attributes)

If this captures the essence of what you are trying to model, then attributes like 'min

stock level' and 'reorder level' would be atributes of product. 'Stock level' could be a

derived attribute determined thus (stock level = opening stock level + purchases - sales).

Hope this helps.

Tony
"mercer876" <member46209_at_dbforums.com> wrote in message news:3536427.1067443092_at_dbforums.com...
>
> hi, i was just wondering if anyone can help me with normalisation and
> especially boyce codd normal form. i have got 10 tables put together, in
> th ehope they are in third normal form, but im not sure, and i require
> them to be in boyce codd form also:
>
>
>
> customer(customerid, cname, caddress,dadress,cpostcode,ctelno)
>
> product(productid,stockid,producttypeid,pname,pprice,siteid)
>
> producttype(producttypeid,preoducttype,descritpion)
>
> site(siteid,sname,saddress,spostcode,stelno)
>
> credit(creditno,credtlimit)
>
> stock(stockid,predocutid,producttypeid,stocklevel,minlevel,reorderlevel-
> ,supplierno)
>
> orders(orderno,customerid,productid,producttypeid,creditno,siteid,stock-
> id,paymentid,supplierno)
>
> payment(paymentid,customerid,feepaid,feedue,dateofpayment)
>
> supplier(supplierno,suppliertypeno,siteno)
>
> suppliertype(suppliertypeno,supplierdescription)
>
> please if there is anyone out there could they help me thanks alot
>
>
> --
> Posted via http://dbforums.com
Received on Fri Oct 31 2003 - 04:43:13 CET