Thanks for your help. ________________________________
From: Peter Brawley [mailto:[EMAIL PROTECTED] Sent: Thursday, August 02, 2007 10:47 AM To: Weston, Craig (OFT); mysql@lists.mysql.com Subject: Re: [mysql] reverse join Craig >How do I pull out all the non-duplicate records? With an exclusion join. To find non-duplicates with respect to one key... SELECT keycandidate FROM tbl t1 LEFT JOIN tbl t2 ON t1.keycandidate=t2.keycandidate WHERE t2.keycandidate IS NULL; To expand the comparison to multiple keys... SELECT key1, key2, ... FROM tbl t1 LEFT JOIN tbl t2 ON t1.key1=t2.key2 AND t1.key2=t2.key2 AND ... WHERE t2.key1 IS NULL; PB Weston, Craig (OFT) wrote: Hi there, I have a situation where I have duplicate data within several tables, but they are all indexed in the same way. How do I pull out all the non-duplicate records? Would I have to create a temporary table, add one data set, then add the second where it doesn't equal the first, and then do the same with the third? Or is there a cleaner way? Thanks, Craig -------------------------------------------------------- This e-mail, including any attachments, may be confidential, privileged or otherwise legally protected. It is intended only for the addressee. If you received this e-mail in error or from someone who was not authorized to send it to you, do not disseminate, copy or otherwise use this e-mail or its attachments. Please notify the sender immediately by reply e-mail and delete the e-mail from your system. ________________________________ No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.476 / Virus Database: 269.11.2/931 - Release Date: 8/1/2007 4:53 PM
