Glad we have this feature added.
But are the CHOOSE function and its also-new-to-SQL-Server-2012 buddy IIF anything other than syntactical sugar for Visual Basic coders writing T-SQL? The CHOOSE function is just a less-flexible shorthand for the ANSI-standard CASE, and it can only be used when evaluating an equality condition for an integer value (the index argument), although I concede that CHOOSE requires less typing than CASE in these limited circumstances. Similarly, the IIF function saves a few keystrokes when there are only two possible values to return, but once you start nesting IIF statements, the code becomes more difficult to understand than the equivalent CASE expression, in my opinion.
SQL Server 2012 just converts CHOOSE and IIF function calls to CASE expressions anyway. I have a code sample that shows that the CHOOSE and IIF functions produce Compute Scalar operators that have Defined Values that are identical to the one produced by the equivalent CASE expression, but I'm having some trouble posting it. I'll try again later.Edit:
I have posted a screenshot of the code, a .txt file of the code, and a .sqlplan file of the execution plan that I get on my SQL Server 2012 instance, if you're interested. Still not sure why I can't post code - I get an error screen that suggests that my employer is blocking the outgoing traffic when it includes certain kinds of code snippets - hmmm . . .