Re: A Logical Model for Lists as Relations

"Marshall Spight" <marshall.spight_at_gmail.com> wrote in message news:1147218113.519014.27620_at_e56g2000cwe.googlegroups.com...
> I am interested in the question of how best to handle lists in a
> relation-oriented world. I have considered various approaches,
> usually oriented around adding a list collection type.
>

This reply is way off topic, and I apologize if it's a distraction.

Oracle makes a distinction between a select that produces a result set, and a select that produces something else, something that might well be called a list. (I forget what Oracle documentation calls it).

The distinction is based on the presence or absence of the "ordered by clause". A SELECT ... ORDERED BY gives a list, while the other kind gives a set.

 This shows up in an odd way: you can't put an "ORDERED BY" in the select that implements a view. If you do, you'll get an error message.

Other SQL DBMS products, like DEC Rdb, have no such restriction on views. You can have a view with an ORDERED BY. You can use such a view in a context where a set would be expected. When I do that, I get the result I would have expected.

This seemed so intuitive to me that I scarcely realized the issue until I moved to a product that forbids it. Received on Wed May 10 2006 - 06:20:48 CDT