sql server 2008 - T-SQL error with IIF keyword -

i have following sql comparison using iif keyword

declare @a int, @b int set @a = 10 set @b = 20  begin    select iif( @a < @b, 'true', 'false') result end 

however, on execution gives error

incorrect syntax near '<' 

what causing this?

as mentioned in comments, iif new function in sql server 2012+, you'll have use case statement instead:

declare @a int, @b int set @a = 10 set @b = 20  begin    select case when @a < @b 'true' else 'false' end result end