Re: erd to db
Date: Tue, 26 Mar 2002 18:02:29 +0100
Message-ID: <3ca0a933$1_at_news.uia.ac.be>
3. The columns of point 1. are indicated as a foreign key to the table for the entity/relationship, if it exists. If it does not exist then the target becomes the table where the relationship is represented by a foreign key. (This happens for certain identifying relationships and one-to-many/one relationships.)
> - Non-identifying one-to-many relationships do *not* get their own table:
This should have been:
- Non-identifying one-to-many relationships without singlevalued attributes
do *not* get their own table:
> - Non-identifying one-to-one relationships do *not* get their own table:
This should have been:
Apologies for the inconvenience. As a final remark let me say that you might
consider to always map a relationship to a table, but in some cases (esp.
identifying relationships) this gives you a redundant database scheme where
the relationship-table is simply the projection of the weak-entity table.
- Non-identifying one-to-one relationships without singlevalued attributes
do *not* get their own table:
Received on Tue Mar 26 2002 - 18:02:29 CET