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From: rob.bbs@shark.cs.fau.edu (Robert Rittenhouse)
Newsgroups: comp.databases
Subject: Re: SQL Duplicate Row Deletion ???
Message-ID: <yqTXZ1w163w@shark.cs.fau.edu>
Date: 5 Apr 91 15:48:09 GMT
References: <1991Apr3.201506.14255@sequent.com>
Sender: bbs@cs.fau.edu (Waffle BBS)
Organization: Florida Atlantic University
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> In article <1991Apr3.010838.2063@eng.ufl.edu> tsao@helios.tcad.ee.ufl.edu wri
> >I am now using Ingres, I am surprised that it allows the user to append 
> >duplicated rows (including a null row) into a table unless you define a key
> >using create unique index.
> >
> >Would anybody give me an example justifying the need for duplicated tuples
> >in a table ?
> >
> > 
An example: I'm doing a parts explosion which consists of recursively
searching a parts tree (a fun trick in and of itself) and inserting
the components required in a parts required table. Sometimes two
parts will use the same component--hence two identical rows will
be inserted in the parts required table. Certainly could avoid doing
so by having a sequence number or some such unique identifier but
there seems no good reason to do so.
(I fix the parts table when finished with the explosion, btw).
Rob R.