Pls Help W/ A Query To Return Running Balances From The Previous Rolling 3 Month Period.

Please refer to this table in this discussion:






Charges

Date


1

1/1/07


2

2/1/07


3

3/1/07


4

4/1/07


5

5/1/07


6

6/1/07


7

7/1/07


8

8/1/07


9

9/1/07


10

10/1/07


11

11/1/07


12

12/1/07
What i'm trying to do is return a result with total charges from 3 months previous based on a date parameter or just as a whole for that matter. For example:

If my date parameter is 6/14/07, i'd like my total charges to be 15 (6+5+4).
If my date parameter is 7/10/07, the charges would be 18 (7+6+5)

I hope that makes sense of where i'm going with this. I've played with this using the "Guru's Guide" solution by Ken Henderson, but still to no avail yet. Here's his code syntax:





Code Block

SELECT a.DayCount, a.Sales, SUM(b.Sales)
FROM Sales a CROSS JOIN Sales b
WHERE (b.DayCount <= a.DayCount) AS RunningTotal
GROUP BY a.DayCount,a.Sales
ORDER BY a.DayCount,a.Sales
Here is the result set i'm looking for:






Charges

Date


1

1/1/07


2

2/1/07


6

3/1/07


9

4/1/07


12

5/1/07


15

6/1/07


18

7/1/07


21

8/1/07


24

9/1/07


27

10/1/07


30

11/1/07


33

12/1/07
Each date's charges are a culmination of 3 months worth of charges.

Any help would be greatly appreciated. I'll be trying to figure this one out concurrently and if i do, i'll post back!

Thanks in advance!