Re: Field Order via Oracle ODBC

Hello,

ERWIN would disagree with you. If you create a child relationship in ERWIN, you MUST have a concatenated key as the primary key (at least that's how it was in version 2.6). The first field(s) would be the foreign key. It made a lot of sense to me.

INVOICE
Invoice_Id

INVOICE_DETAIL
Invoice_ID (FK)
Invoice_Detail_Line_Number

This continued indefinitely. It helps to establish for certain just what the relationships are. Without them, I was always wondering just what the relationship was. Especially on 1:M:M:M relationships.

I often was looking at schemas that didn't follow ERWIN's convention. When I analysed it, what the designors' thought was a Parent to Child relationship, was actually a Child to Parent; exactly what they didn't want. You should have seen their incredulous looks when I told them that their program could bomb when they did an insert.

Regards,

Argosy

In article <7jm5io$tub$1_at_esinet2.esinet.net>,   "Arvin Meyer" <a_at_m.com> wrote:
> No, that is not they way it is handled in a normalized databased.
>
> Invoice Header -primary key = InvoiceNumber
>
> Invoice Detail - primary key = InvoiceDetailNumber
> foreign key = InvoiceNumber
>
> InvoiceLineNumber is extraneous and doesn't even need to be recorded,
merely
> displayed for the convenience of the viewer. Composite keys should be
> avoided if possible in detail records, unless they are used in a join
table
> in a many-to-many relationship.
> ---
> Arvin Meyer
> onsite_at_esinet.net
>

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Share what you know. Learn what you don't. Received on Thu Jul 08 1999 - 13:15:19 CDT