Transactions/sec using sql query

declare @first_val bigint,@second_val bigint;select
@first_val = cntr_value from master..sysperfinfo where counter_name = 'Transactions/Sec' and
instance_name = 'CBFIRM';Waitfor Delay '00:00:30';
select @second_val = cntr_value from master..sysperfinfo where counter_name = 'Transactions/Sec'
and instance_name = 'CBFIRM';select (@second_val-@first_val)/30 as 'cntr_value'