Question

Possible Duplicate:
Calculate a Running Total in SqlServer

Consider this data

     Day | OrderCount
       1       3
       2       2 
       3       11
       4       3
       5       6

How can i get this accumulation of OrderCount(running value) resultset using T-SQL query

      Day | OrderCount | OrderCountRunningValue
       1        3            3
       2        2            5
       3        11           16
       4        3            19
       5        6            25

I Can easily do this with looping in the actual query (using #table) or in my C# codebehind but its so slow (Considering that i also get the orders per day) when im processing thousand of records so i’m looking for better / more efficient approach hopefully without loops something like recursing CTE or something else.

Any idea would be greatly appreciated. TIA

Answer 1

As you seem to need these results in the client rather than for use within another SQL query, you are probably better off Not doing this in SQL.

(The linked question in my comment shows ‘the best’ option within SQL, if that is infact necessary.)

What may be recommended is to pull the Day and OrderCount values as one result set (SELECT day, orderCount FROM yourTable ORDER BY day) and then calculate the running total in your C#.

Your C# code will be able to iterate through the dataset efficiently, and will almost certainly outperform the SQL approaches. What this does do, is to transfer some load from the SQL Server to the web-server, but at an overall (and significant) resource saving.