Happy New Year My dear Friends 
It’s been a long this feature has been released however I just got an opportunity to check it out. This feature is released in SQL Server 2008 version. Sparse columns are normal columns which will store NULL values in a optimized storage which means no storage space is taken when you store NULL values to that column. Happy !! there is some overhead for storing non NULL values to this columns, it will take some more space for non NULL values.
Microsoft released 3 new conversion function in SQL Server Denali. In which two functions will tell you whether the action is possible the third one will give you the result. Below are the three conversion functions
SQL Server Denali comes with one more new logical function which helps to pull data at the specified index from a list of values. CHOOSE() is the function that’s been added. Again this function exists in Access , so if you migrate the db from Access there is no need to rewrite your query using CASE statement. In simple this function is a short form of CASE statement.
IIF function is new to SQL Server Denali however if you worked with MS Access then you are familiar with this function. So if you are upgrading a database from Access to SQL Server Denali you don’t need to worry about rewriting the IIF function queries. IIF function will evaluate the expression and it will return one value out of two input values. This function is similar to CASE function however you can evaluate the expression for two values and not more than that.
Yesterday we discussed about time function, today we are going to see DATEFROMPARTS function which is new in SQL Server Denali. It will return a date value for the specified year, month and day. All the arguments should be valid else error is thrown, if you have NULL value in argument then NULL is returned.