Martjin, Of course one should use the right JOIN for the job. But let me ask you, which join would you use here?
You have a table called Descriptors, it has a field called nameID which is a unique key that relates to a Names table made up of a unique identity and a VARCHAR name. I think most people would write a simple query like this: SELECT desc.<fields>, names.name FROM desc JOIN names ON desc.nameId = names.Id ORDER BY names.name However, it this really correct? Every descriptor has a record in names, so it could be equivalently written as: SELECT desc.<fields>, names.name FROM desc RIGHT JOIN names ON desc.nameId = names.Id ORDER BY names.name My guess is that most people conventionally write the first query. R. -----Original Message----- From: Martijn Tonies [mailto:[EMAIL PROTECTED] Sent: Tuesday, March 21, 2006 1:01 AM To: mysql@lists.mysql.com Subject: Re: RIGHT JOIN better than INNER JOIN? > I apologize if this is a naive question but it appears through my > testing that a RIGHT JOIN may out perform an INNER JOIN in those cases > where they would produce identical result sets. i.e. there are no keys > in the left table that do not exist in the right table. > > Is this true? If so, it this peculiar to MySQL or would this be true > with almost all database servers? i.e. Oracle, DB2, MSSQL, etc. Use the join that is appropriate for your query, do not use a different one. If speed isn't OK, then bug the guys that do the implementation, but don't start changing the query that _might_ return a different result if, for example, someone else starts working at the application and figures "hey, this is a right join, so it's optional" etc ... Martijn Tonies Database Workbench - development tool for MySQL, and more! Upscene Productions http://www.upscene.com My thoughts: http://blog.upscene.com/martijn/ Database development questions? Check the forum! http://www.databasedevelopmentforum.com -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED] -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
