Re: About Entity Relation Diagram

From: Alfredo Novoa <alfredo_novoa_at_hotmail.com>
Date: Thu, 16 Dec 2004 14:31:35 GMT
Message-ID: <41c19be3.13488406@news.wanadoo.es>

On 16 Dec 2004 05:18:21 -0800, "Mark D Powell" <Mark.Powell_at_eds.com> wrote:

>Splitting data that shares the same PK into multiple tables is
>denormalized.

No, it is not. It does not violate any normal form.

>Now, if the combined length of the columns exceeds the maximum row
>length supported by your RDBMS then you will have to split the rows
>into pieces each of which will have to be stored in a separate table,
>but the tables will share the same PK. This is a case where the
>physical implementation has to vary from the logical design due to
>limitations in the software.

This is a case where the logical design has to change due to limitaitons in the DBMS.

The table design is the logical design. The ER design is a conceptual design.

Regards Received on Thu Dec 16 2004 - 08:31:35 CST