My friend and Guide Jacob Sebastian who is an Microsoft SQL Server MVP running a very popular series of TSQL on his site beyondrelational.com. If you know something about SQL Server then this challenge is for you. And if you are master of SQL then this challenge is for you to test you knowledge. If you have some time and If you want to test you knowledge or you want enhance your knowledge challenge then please spare some time to take it. Here is link for that.
Currently he is running TSQL Challenge Number 35 which is about fine number full attendee for a conference.