RE: gnarly delete statement?

From: Mohan, Ross <MohanR_at_STARS-SMI.com>
Date: Thu, 01 Nov 2001 13:11:48 -0800
Message-ID: <F001.003BACF9.20011101131519@fatcity.com>

don't suppose you can properly
normalize the tables through
materialized views and update
the "pk" through that, eh?

-----Original Message-----
Sent: Thursday, November 01, 2001 3:56 PM To: Multiple recipients of list ORACLE-L

Given a business rule that says a combination of three columns must be unique if and only if a fourth column equals a certain value, and if the table in question contains rows that violate this requirement, I'm trying to write a single SQL statement that will remove the duplicates.  Of each set of duplicate rows, I'll delete the one with the latest insert timestamp.

Let's call the columns

a b c d timestamp

The combination of b, c, and d must be unique if a = 2.

I can get the duplicate row values along with the latest timestamp via

select max(tstamp), a, b, c from
my_table group by a, b, c having count(*) > 1

But I can't figure out how to use that in a delete statement.

Suggestions greatly appreciated!

Paul Baumgartel

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Author: Paul Baumgartel
  INET: treegarden_at_yahoo.com

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Author: Mohan, Ross
  INET: MohanR_at_STARS-SMI.com

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To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). Received on Thu Nov 01 2001 - 15:11:48 CST