Re: By The Dawn's Normal Light

Dawn M. Wolthuis wrote:
>>It can if you want it to; I can certainly understand a DBMS vendor
>>offering lists as a built-in type. But it's not important for the DBMS
>>to know any more about the List than about the Set or the Date or
>>the... offering them would just be a convenience. It doesn't affect
>>relational theory or practice.

> 
> I agree that the database need not know more about a List or Set than about
> a Date, but why does it need to know more about a Relation than about a
> List?  Thanks.  --dawn

Because a relation represents a logical predicate, and that is the fundamental part of a DBMS. And a collection of propositions don't have any intrinsic order, so they just need to be a set, not a list. The ability to have columns/values of different types is just the icing on the cake.

Paul. Received on Fri Oct 29 2004 - 14:01:24 CEST