Re: Sub-Entities in Designer/2000

From: Tim Fitzpatrick <devsupp_at_dial.pipex.com>
Date: 1997/07/03
Message-ID: <33bb2655.27030185_at_news.dial.pipex.com>#1/1


There is another alternative:

Resolve the sub-typing explicitly in the entity model before using the DDW. To elaborate:

Seperate the employee entity out from the person entity and link the two with a one-to-one relationship, mandatory at the employee end but optional at the person end.

This will result (post-DDW) in two tables, persons and employees, with a foreign key from persons to employees.

Thus, a person need not be an employee and an employee must have an associated person record.

If there is more than one sub-type, you start to get into the "arc at the supertype" end scenario, but that's another story...

Personally I hate subtyping (especially having recently picked up a data model with 13 levels of it that an Oracle consultant had kindly advised my new company was the best way of implementing their solution).

If you must use subtypes keep them to an ABSOLUTE minimum.

Sorry, I've started ranting. Time to go.

Cheers,

        Tim Received on Thu Jul 03 1997 - 00:00:00 CEST

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