Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!usc!samsung!munnari.oz.au!csc!csc3.anu.oz!ccadfa!ghm
From: ghm@ccadfa.adfa.oz.au (Geoff Miller)
Newsgroups: comp.databases
Subject: Re: Time related records
Keywords: time,database
Message-ID: <1689@ccadfa.adfa.oz.au>
Date: 29 Jun 90 07:03:27 GMT
References: <1082@kirk.nmg.bu.oz> <1990Jun28.160558.1974@ultra.com>
Organization: Computer Centre, University College, UNSW, ADFA, Canberra, Australia
Lines: 21

In <1082@kirk.nmg.bu.oz> cameron@kirk.nmg.bu.oz (Cameron Stevenson) writes:

>We are holding information within a table for a key register. Some of
>the columns are the key number, the person the key is issued to, and
>the issue date. Now supposing that person leaves, the key is handed in
>and issued to a new person. Now the information within the table is
>altered to reflect that change, but the problem... how can I store
>the fact that at some stage person A was issued with that key.

We had a similar problem with a File Registry System, where we need to
identify the current location of a file *quickly* but also record the
movement history.  We store the location as a multivalued field, and
at every movement insert the new location as the first multivalue.  An
associated MV field record the date of the movement, so we can if necessary
strip off movements preceding a given date.  

Of course, we are working with a Pick-like system (Prime "Information")
which makes this kind of thing very easy....

Geoff Miller
ghm@cc.adfa.oz.au