Solved

MySQL: Finding Oldest Douplicate

Posted on 2014-02-11
3
259 Views
Last Modified: 2014-02-11
The returns the bookkey and updated time of duplicate items:
SELECT elqBooks.isbn, elqBooks.updated
 FROM elqBooks 
 GROUP BY elqBooks.ISBN HAVING count(elqBooks.isbn) > 1

Open in new window

I want the OLDEST item to be selected.  How can I get the OLDEST matching duplicated item?
0
Comment
Question by:hankknight
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
3 Comments
 
LVL 35

Accepted Solution

by:
Dan Craciun earned 500 total points
ID: 39850012
SELECT elqBooks.isbn, MIN(elqBooks.updated)
 FROM elqBooks
 GROUP BY elqBooks.ISBN HAVING count(elqBooks.isbn) > 1
0
 
LVL 16

Author Comment

by:hankknight
ID: 39850068
Thanks.  Now how can I do this with the bookkey only?  I only want the bookkey of the oldest douplicate record to be included.
SELECT elqBooks.bookkey
 FROM elqBooks 
 GROUP BY elqBooks.ISBN HAVING count(elqBooks.isbn) > 1

Open in new window

0
 
LVL 11

Expert Comment

by:John_Vidmar
ID: 39850188
Without knowing your schema, would you be able to take the results of the group-by/min and join back to your table to get the key?
SELECT	a.bookkey
FROM	elqBooks	a
JOIN	(	SELECT	isbn
		,	updated = MIN(updated)
		FROM	elqBooks 
		GROUP
		BY	isbn
		HAVING	count(*) > 1 
	)	b	ON	a.isbn = b.isbn
			AND	a.updated = b.updated

Open in new window

0

Featured Post

NEW Veeam Agent for Microsoft Windows

Backup and recover physical and cloud-based servers and workstations, as well as endpoint devices that belong to remote users. Avoid downtime and data loss quickly and easily for Windows-based physical or public cloud-based workloads!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Does the idea of dealing with bits scare or confuse you? Does it seem like a waste of time in an age where we all have terabytes of storage? If so, you're missing out on one of the core tools in every professional programmer's toolbox. Learn how to …
Introduction This article is intended for those who are new to PHP error handling (https://www.experts-exchange.com/articles/11769/And-by-the-way-I-am-New-to-PHP.html).  It addresses one of the most common problems that plague beginning PHP develop…

740 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question