Actually it's the combination of the columns that are unique. I have used filtered indexes before (and think they are a great addition to SQL Server). In this particular case a single unique key worked just fine.
I'm actually somewhat surprised. I expected to have at least one person disagree with me.
Kenneth FisherI was once offered a wizards hat but it got in the way of my dunce cap.--------------------------------------------------------------------------------For better, quicker answers on T-SQL questions, click on the following... http://www.sqlservercentral.com/articles/Best+Practices/61537/[/url]For better answers on performance questions, click on the following... http://www.sqlservercentral.com/articles/SQLServerCentral/66909/[/url]Link to my Blog Post --> www.SQLStudies.com[/url]