This is more of a philosophical issue than anything, but it has jumped up to bite us so I thought I'd make others aware;
Since NULL has no value they can be entered multiply times into unique columns. Some will say that NULL is a value and therefore should be unique in this case (only one NULL allowed) and others will say that since NULL has no intrinsic value it can be entered into a unique column as many times as you would like. We have found this behavior in multiple database types (MS-SQL, Oracle) so it is not unique to MySQL, it is just where we noticed it. It is not one of those things that we thought about....until now! -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
