From: | "Sander Steffann" <steffann(at)nederland(dot)net> |
---|---|
To: | "Curt Sampson" <cjs(at)cynic(dot)net>, "Christopher Kings-Lynne" <chriskl(at)familyhealth(dot)com(dot)au> |
Cc: | "Hannu Krosing" <hannu(at)tm(dot)ee>, "Hackers" <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Why is MySQL more chosen over PostgreSQL? |
Date: | 2002-07-31 08:35:12 |
Message-ID: | 008301c2386d$301f8d00$8e01a8c0@OFFICE |
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Thread: | |
Lists: | pgsql-hackers |
Hi
> And what's the problem with networkcard_products being a separate table
> that shares a key with the products table?
>
> CREATE TABLE products (product_id int, ...)
> CREATE TABLE networkcard_products_data (product_id int, ...)
> CREATE VIEW networkcard_products AS
> SELECT products.product_id, ...
> FROM products
> JOINT networkcard_products_data USING (product_id)
>
> What functionality does table inheritance offer that this traditional
> relational method of doing things doesn't?
Well, if you also have soundcard_products, in your example you could have a
product which is both a networkcard AND a soundcard. No way to restrict that
a product can be only one 'subclass' at a time... If you can make that
restriction using the relational model, you can do the same as with
subclasses. But afaict that is very hard to do...
Sander.
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