SQL Fastest way to Group records based on Thresholds - sql-server-2008

Question

My records are in a temporary table having three columns :
Column1 : ID (Bigint)
Column2 : CreationDateTime (dateTime)
Column3 : Volume (Float)
The records are sorted based on CreationDateTime.
I need to pick the records from the table where Sum of Volume is equal to THRESHOLD1 and then the same for Threshold2.
One way is to add a new Column to the table which has the sum of Volume for the previous records. for example :
ID - CreationDateTime - Volume - SUM
1 - 20/07/2012 - 10 - 10
2 - 21/07/2012 - 12 - 22
3 - 22/07/2012 - 7 - 29
and then Select * from temp where Sum >= Threshold But the calculation of the sum is not the fastest way.
I was wondering if anyone can suggest a better way for doing the above.
I'm using SQL server 2008 and I can also use CLR if required.

Answer 1

try this solution:
you can find the running total just by self joining tables and group by
with cte as(
select T2.ID, T2.CreationDateTime,SUM(T1.Volume) [SUM]
from test_table T1 join test_table T2
on T1.id<=T2.id
group by T2.id, T2.CreationDateTime)
select * from cte where [SUM]>= Threshold

Answer 2

Here's an approach using a recursive CTE, which will likely be the fastest:
select #i=min(ID) from #temp
;with a as
(
select ID, Volume, Volume as RunningTotal
from #temp
where ID=#i
union all
select b.ID, b.Volume, b.Volume + a.RunningTotal as RunningTotal
from #temp b
inner join a
on b.ID=a.ID+1
)
select * from a
Some links related to running totals:
http://www.sqlusa.com/bestpractices/runningtotal/
http://www.databasejournal.com/features/mssql/article.php/3112381/SQL-Server-Calculating-Running-Totals-Subtotals-and-Grand-Total-Without-a-Cursor.htm
http://www.mssqltips.com/sqlservertip/1686/calculate-running-totals-using-sql-server-cross-joins/
http://social.msdn.microsoft.com/Forums/eu/transactsql/thread/1b4d87cb-ec77-4455-af48-bf7dae50ab87
Computed Column using a function:
create function dbo.fn_VolumeRunningTotal
{
#dt datetime
}
returns int
as
begin
declare #total int
select #total = sum(volume)
from dbo.MyVolumeTable
where CreationDateTime <= #dt
return #total
end
Computed Column formula:
dbo.fn_VolumeRunningTotal(CreationDateTime)
Select statements:
select * from dbo.MyVolumnTable where RunningTotal <= #Threshold1