Bill, here is one approach: The following query will return the id's that should NOT be deleted: Select min (id) from icd9x10 group by icd9, icd10
Once you run it and happy with the results then you subquery it in a DELETE statement. Something like: Delete from icd9x10 A where A.id not in (Select min (B.id) from icd9x10 B group by B.icd9, B.icd10). I have not tested it (sorry it is a weekend here...), but I hope it will lead you into the right direction. David. David Lerer | Director, Database Administration | Interactive | 605 Third Avenue, 12th Floor, New York, NY 10158 Direct: (646) 487-6522 | Fax: (646) 487-1569 | dle...@univision.net | www.univision.net -----Original Message----- From: william drescher [mailto:will...@techservsys.com] Sent: Saturday, March 29, 2014 2:26 PM To: mysql@lists.mysql.com Subject: Help with cleaning up data I am given a table: ICD9X10 which is a maping of ICD9 codes to ICD10 codes. Unfortunately the table contains duplicate entries that I need to remove. CREATE TABLE `ICD9X10` ( `id` smallint(6) NOT NULL AUTO_INCREMENT, `icd9` char(8) NOT NULL, `icd10` char(6) NOT NULL, PRIMARY KEY (`id`), UNIQUE KEY `icd9` (`icd9`,`id`), UNIQUE KEY `icd10` (`icd10`,`id`) ) ENGINE=InnoDB AUTO_INCREMENT=671 DEFAULT CHARSET=ascii id icd9 icd10 25 29182 F10182 26 29182 F10282 27 29182 F10982 I just can't think of a way to write a querey to delete the duplicates. Does anyone have a suggestion ? bill -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/mysql The information contained in this e-mail and any attached documents may be privileged, confidential and protected from disclosure. If you are not the intended recipient you may not read, copy, distribute or use this information. If you have received this communication in error, please notify the sender immediately by replying to this message and then delete it from your system.
