declare 
	@yyyy char(4)
,	@mm char(2)

set @yyyy = '2011'
set @mm = '04' --현재가 4월 12일 이라면..

;with t
as
(
	select convert(date, '2011-04-12') date_key union all
	select convert(date, '2011-03-01') date_key union all
	select convert(date, '2011-02-01') date_key 
)
select
	left(date_key,7) + 
	case when convert(char(7), getdate()-1, 121) = @yyyy + '-' + @mm and 
		left(date_key,7) = @yyyy + '-' + @mm  then 
			'(' + @yyyy + '-' + @mm + '-01 ~ ' + convert(char(10), getdate()-1, 121) + ')' 
	else '' end
from t		
order by 1

/*
2011-02
2011-03
2011-04(2011-04-01 ~ 2011-04-12)
*/