Re: Entity R Diagrams/Case

wayne_at_netcom.com writes in article <wayneC920zv.HEs_at_netcom.com>:
>
> Ok, here is any easier one? Does the Oracle Case ER Diagram tool somehow
> generate the necessary tables from the diagram?

The ER-diagrammer itself does not generate tables - CASE dictionary has functions to do this

> I mean, at some point,
> in the ER diagram game, doesn't someone actually have to generate tables
> for each of the entitites (which I assume are really tables).

This is, IMO, one of the biggest misunderstandings with ORACLE Case and Entitys.

With entitys and their relations, you describe your "business data and their relations" - and the point is you describe _everything_, if you will need it in your application or not. _Which_ of the entitys you are implementing in the application and _how_ you do it depends on you - it is not forced by the CASE-tool. You even do have external entitys, which can describe things "outside" - for example, a fax letter, printout or something else.

The ER-diagrams are _independent_ from the actual table implementation. For example, it is perfectly valid to describe a relationship like this:

         Entity A >-------< Entity B

One will never be able to implement such a design without a so called intersection table:

         Table A -------< Table C >------ Table B

The "default database designer" can generate these tables for you.
>
> --
> Wayne T. Watson wayne_at_netcom.com (415) 969-4233
> Mountain View, CA
>

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