To: Jodi Kanter <jkanter@virginia.edu>
Cc: Postgres SQL List <pgsql-sql@postgresql.org>
Subject: Re: duplicate dates  
From: Christopher Browne <cbbrowne@libertyrms.info>
Date: Fri, 01 Aug 2003 11:57:44 -0400
Message-ID: <60oez9l69z.fsf@dev6.int.libertyrms.info>
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Jodi Kanter wrote:
> I have one table that has a date/time field in it. I'd like to identify  
> the records in the database where the date/time fields are the same. How  
> can I do this? Do I need to create a view or temp table? Is there a way  
> to run through one table multiple times. 

If you plan to review the data multiple times, and the table is rather
large, then it probably makes sense to make a temp table.

  select a.* into temp table my_dupes from
         dated_table a, dated_table b
   where a.event_on = b.event_on
     -- Assuming that the primary key is on (field1, field2, field3)
     and a.key_field1 <> b.key_field1
     and a.key_field2 <> b.key_field2
     and a.key_field3 <> b.key_field3;

You could then rummage through my_dupes as needed.  Note that if there
are more than 2 simultaneous records, it will list all of them
multiple times :-(.

You may also want to be more precise about what you mean by 'date/time
fields are the same'.  They go down to fractions of a second, so you
shouldn't have a huge number of collisions.
-- 
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Christopher Browne
(416) 646 3304 x124 (land)