Re: Lucid statement of the MV vs RM position?

From: dawn <>
Date: 24 Apr 2006 10:47:29 -0700
Message-ID: <>

Tony Andrews wrote:
> dawn wrote:
> > 'The entire information content of a relational database is
> > represented in one and only one way: namely, as attribute values within
> > tuples within relations.'"
> <SNIP>
> > Are you suggesting that there have been implementations where list
> > attributes have been defined (as UDTs) in such a way that the query
> > language understands and properly handles values that are lists
> > (ordered)? When defining this type, is it easy enough to implement it
> > so that ALL and EVERY (or whatever) will function properly from SQL
> > against these lists (not just against RVAs)?
> Why would the query language have to understand lists?

To make things easier (less expensive) for users (developers and end-users)

> The whole point
> of UDTs is that they are User Defined, which means that their
> implementation and meaning is not known to the query language.

That is how I understood it too.

> definer of the UDT would define "operators" (aka "methods") to do the
> things that can be done with values of that UDT, and you could use
> those operators in your queries. Lists are just one of a squillion
> UDTs that could be defined, and surely you don't expect the DBMSs
> built-in query language to "understand" them all?

Nope, just lists, lists of lists (2D arrays), sets, and scalars. --dawn Received on Mon Apr 24 2006 - 19:47:29 CEST

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