Re: Multiplicity, Change and MV
Date: Tue, 11 Apr 2006 17:45:17 +0300
Message-ID: <e1gfct$7l6$1_at_emma.aioe.org>
"JOG" <jog_at_cs.nott.ac.uk> wrote in message
news:1144686256.966117.179590_at_e56g2000cwe.googlegroups.com...
> Change bothers me. Especially in database schema, and specifically when
What schema ?
> we want to accomodate change in the cardinalities of the relationships
> we are modelling.
> This is what I'd like to focus on here - I am interested in exploring
> how one might reduce the dependency between query-form and
> db-structure.
It occured to me that perhaps a command line interface would be better for the task. :-)
>--------------------------
>MV - Set/List value approach (Pick?):
>--------------------------
>Courses = { (name:French), (name:English), (name:German) }
>Lecturers = {
> (id:1, name:Tom, teaches: {French, German} ),
> (id:2, name:Bob, teaches: English )
>}
How about
Lecturers = {
(id:1, name:Tom, {teaches: {French, German}, play {tennis}} ),
(id:2, name:Bob, {teaches: English, play{violin}} )
}
> Immediately I've lost the added functionality of having a teaching
> relation - but that's not a current concern because *at the moment* I'm
> focusing on preserving query form. A greater concern is that a set (or
> list if one prefers) has now materialized where previously none
> existed.
What if something else materialize suddenly ? :-) Received on Tue Apr 11 2006 - 16:45:17 CEST