Table links and PKs

Design tools I have complain when I try to set up a table with a multi-field Primary Key (PK) with one field only linked as a Foreign Key (FK) to the PK of another table.

However this configuration often seems natural to me. Can anyone explain?

Example of how I might choose to use it is in a Contacts telephones table:

    CONTACTS
-> Contact_Id PK

|     ...Other fields
|
|    PHONES
|    PhoneNumber   PK1
|_   Contact_Id           PK2

As multiple contacts may share the same telephone number, PhoneNumber on its own is not an appropriate PK.

Because my design tool complains I usually add a surrogate PK and put a unique index on the two fields above.

Why is the above design perceived as flawed?

Thanks,
Clive. Received on Tue Aug 06 2002 - 14:01:53 CDT