Choose in SQL Server 2012

Overview

SQL Server 2012 has introduced 2 new logical functions. IIF & Choose.
Let's go over CHOOSE function. It returns a value at specific index from a list. 

Scenarios & Example

•  Basic Use

SELECT CHOOSE(3, 'SQL 2005', 'SQL 2008', 'SQL 2012')

(No column name)

SQL 2012

So we can see that, it gives 3rd value from the set of value we have provided. 
Let's test if we give some unusual index values

SELECT 'CASE 1.1' [Case], CHOOSE(1.1, 'SQL 2005', 'SQL 2008', 'SQL 2012')  [Value]

UNION ALL

SELECT 'CASE 1.9' , CHOOSE(1.9, 'SQL 2005', 'SQL 2008', 'SQL 2012')

UNION ALL

SELECT 'CASE -3' , CHOOSE(-3, 'SQL 2005', 'SQL 2008', 'SQL 2012')

UNION ALL

SELECT 'CASE 5' , CHOOSE(5, 'SQL 2005', 'SQL 2008', 'SQL 2012')

Case	Value
CASE 1.1	SQL 2005
CASE 1.9	SQL 2005
CASE -3	NULL
CASE 5	NULL

•  Advance Use

Let's say, we have a date stored in a table, we want to know whether it is weekday/weekend, then this is how we can write using CHOOSE.

SELECT EmployeeName,EmployeeDOB, DATENAME(DW,EmployeeDOB), DATEPART(DW,EmployeeDOB),

CHOOSE(DATEPART(DW,EmployeeDOB), 'WEEKEND', 'Weekday', 'Weekday', 'Weekday', 'Weekday', 'Weekday', 'WEEKEND') FROM Employee

EmployeeName	EmployeeDOB	(No column name)	(No column name)	(No column name)
John	4/4/1989	Tuesday	3	Weekday
Rob	5/28/1990	Monday	2	Weekday
Bob	3/16/1991	Saturday	7	WEEKEND
Ryan	12/5/1983	Monday	2	Weekday
Lisa	9/14/1979	Friday	6	Weekday

We can also write the same thing using CASE statement but the only thing CHOOSE will be easier to write than CASE.
w.r.t Performance, there is no difference either you use CASE or CHOOSE, both are same. CHOOSE internally uses CASE only.