Re: normalisation

Originally posted by mercer876

> 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,reorderlev-
> el,supplierno)

> orders(orderno,customerid,productid,producttypeid,creditno,siteid,sto-
> ckid,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
>

It's almost impossible to tell, because normalisation requires knowledge of the functional dependencies of your data; we can only make guesses. There is no magic formula. But this strikes me as unlikely to be correct:

orders(orderno,customerid,productid,producttypeid,creditno,siteid,stockid, paymentid,supplierno)

Why is producttypeid there, surely that is functionally dependent on productid? I'm not sure about siteid either.

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