Curt Sampson wrote:
> On Wed, 31 Jul 2002, Christopher Kings-Lynne wrote:
> > > I highly doubt that. Relating two tables to each other via a key, and
> > > joining them together, allows you to do everything that inheritance
> > > allows you to do, but also more. If you have difficulty with keys and
> > > joins, well, you really probably want to stop and fix that problem
> > > before you do more work on a relational database....
> > I'm still not convinced of this. For example, my friend has a hardware
> > e-store and every different class of hardware has different properties. ie
> > modems have baud and network cards have speed and video cards have ram. He
> > simply just has a 'products' table from which he extends
> > 'networkcard_products', etc. with the additional fields. Easy.
> 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?
You can add children without modifying your code. It is classic C++
inheritance; parent table accesses work with the new child tables
Bruce Momjian | http://candle.pha.pa.us
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