Re: DBDesign Q

It is correct on an ERD, but incorrect in a relational schema.


"Andy" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
> Can two entities have more than one relationship between them?
>
> A(A_ID PK,..., bID FK)
>
> B(B_ID PK,..., aID FK)
>
> A.bID refers to B.B_ID
> B.aID refers to A_ID
>
> 2. Does it make sense?
>
> Product (ProductID PK, Name,., SpecialAttrID FK)
>
> Attribute (AttrID PK, Name,..,ProductID FK)
>
> Product can have many attributes. One attribute belongs to only one
product.
> There is only one main("special") attribute for each product
>
> Thank you in advance,
> Andy