Um, yes, probably need to update my Oracle reference manuals – I think the big fat paper one on my shelf may even refer to ANSI SQL89, which I suspect is pretty much what my head content is based on also. In any case, XOR doesn’t appear to be in the latest ANSI/ISO SQL standards I have access to (ANSI 2003), so this may be a MySQL-specific extension. But however you slice it, XOR is the wrong solution for the problem at hand! ;) Cheers! Mike -- Mike Ford, Electronic Information Developer, Libraries and Learning Innovation, Leeds Metropolitan University, C507, Civic Quarter Campus, Woodhouse Lane, LEEDS, LS1 3HE, United Kingdom Email: m.ford@xxxxxxxxxxxxxx Tel: +44 113 812 4730 From: Ashley Sheridan [mailto:ash@xxxxxxxxxxxxxxxxxxxx] Sent: 07 December 2009 12:26 To: Ford, Mike Cc: php-general@xxxxxxxxxxxxx Subject: RE: [PHP] Re: logic operands problem On Mon, 2009-12-07 at 12:26 +0000, Ford, Mike wrote: This is pretty much why SQL does not offer you the XOR operator! Someone better tell the MySQL developers then... http://dev.mysql.com/doc/refman/5.0/en/logical-operators.html Thanks, Ash http://www.ashleysheridan.co.uk To view the terms under which this email is distributed, please go to http://disclaimer.leedsmet.ac.uk/email.htm