Re: How to code a supertype subtype relationship

<bogstonkott_at_netscape.net> wrote in message news:901972da.0403241318.7ee14071_at_posting.google.com...
> "Tom Hester" <$$tom_at_metadata.com> wrote in message
news:<76b19$4060bb79$45033832$26263_at_msgid.meganewsservers.com>...
> > The two most common ways are the one that you are using and adding the
> > columns of subtypes to the supertype table and allowing attributes of X
for
> > example to be null for a subtype Y.
>
> Well, that confirms pretty much what my co-workers and I were
> thinking. Adding the subtypes to the supertype isn't practical in our
> situation. There is one supertype with ten subtypes.

Perhaps the large number of subtypes indicates some flaw in the design? You aren't programming mammal classification, aren't you? (For huge hierarchies type-subtype paradigm breaks anyway, as one better program generic parent-child relationship instead of making them types).

> The smallest
> subtype has 15 columns. To combine into one table there would be over
> 200 columns. That's not pretty. Thanks.

Thanks god somebody still is able to smell if the design stinks! Normally, people give it much less thought. You might enjoy googling the thread "Stupidest table I ever saw". Received on Wed Mar 24 2004 - 22:43:01 CET