Re: Proposal: 6NF
From: paul c <toledobythesea_at_dbms.yuc>
Date: Wed, 18 Oct 2006 20:40:42 GMT
Message-ID: <ejwZg.157085$5R2.155879_at_pd7urf3no>
> In the context of a dbms engine, a type would be the built in datatypes
> that the engine supports, like INTGER, DECIMAL, CHAR, and DATE, and also
> the builtin functions and operations, like "+" or "weekday(x)".
>
> A domain would be what you get when you say CREATE DOMAIN. It's a set, but
> it has no functions and operations other than the ones it inherits from the
> data type it is based on.
>
> Does this make sense?
>
Date: Wed, 18 Oct 2006 20:40:42 GMT
Message-ID: <ejwZg.157085$5R2.155879_at_pd7urf3no>
David Cressey wrote:
> ...
>> PMFJI, when it comes to a dbms engine, I don't know the difference >> between a type and a domain. >>
> In the context of a dbms engine, a type would be the built in datatypes
> that the engine supports, like INTGER, DECIMAL, CHAR, and DATE, and also
> the builtin functions and operations, like "+" or "weekday(x)".
>
> A domain would be what you get when you say CREATE DOMAIN. It's a set, but
> it has no functions and operations other than the ones it inherits from the
> data type it is based on.
>
> Does this make sense?
>
Ièd say YOU make sense, but IT doesnèt. However, if the difference you
mention is typical usage, I guess Ièll have to accept it. I vaguely
remember using something like CREATE DOMAIN in SQL, perhaps that is
exactly what I used, and being disappointed - I seemed no more than a
name aliasing operator.
p