Re: Retrieval of duplicates, possible??

From: Philip Lijnzaad <lijnzaad_at_ebi.ac.uk>
Date: 2000/05/25
Message-ID: <u7ln0yznal.fsf_at_o2-3.ebi.ac.uk>#1/1


Mark> I think this is a good solution and would probably work as well or
Mark> better than what I want to mention.  The original post mentioned union
Mark> and minus.  Isn't it asking for what the third set operator is designed
Mark> to do, namely, intersect, which shows members common to both sets.

First of all, it wasn't at all clear why there was any need for the comparison between the two tables, Policy and Commission_Policy. If there was, it should have been described better.

Secondly, INTERSECT is also a set operator, and as such doesn't yield _any_ duplicates. So {a, a, b, c} INTERSECT { a, e, f} simply gives { a } (_not_ { a, a }) and {a, a, b, c} INTERSECT { b,e , f} simply gives { b }. So there is nothing that can help you find duplicates. You simply cannot use _any_ set operator to find duplicates. Cheers,

                                                                      Philip

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Received on Thu May 25 2000 - 00:00:00 CEST

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