From: Mike Krolewski <mkrolewski@rii.com>
Newsgroups: comp.databases.oracle.server
Subject: Re: Nested Tables?
Date: Fri, 02 Feb 2001 17:39:13 GMT
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In article <95ek4v$2ic$1@nnrp1.deja.com>,
  jdorlon@my-deja.com wrote:
> Can anyone describe a scenario of when nested tables would be desired?
> They just seem so complicated to me that they are not worth the
> effort!  Am I missing something?
>
> Thanks!
>
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> http://www.deja.com/
>

Exactly. There are some possible uses -- that obviously could be done
other ways. One is a header and detail records. The idea is that one is
always looking at the detail with the header. Access speed is improved
as the detail rows are immediately accessible. Major problem is the
limit to the number of nested rows. A second issue is that your
business rules will change, and the reason to keep the detail
immediately close to the header will go away.

A significant use would be duplicating another system --> COBOL or ISAM
for instance where this structure is common. Useful in quickly
transferring from one system to another. IMHO not the best data design.

Practically, IMHO nested tables is a solution in search of a problem.

--
Michael Krolewski
Rosetta Inpharmatics
mkrolewski@rii.com
              Usual disclaimers


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