Asking For Help With Distinct Count Within Rolling Period...

Thanks for taking the time to read my post. I greatly appreciate it!

What i'm trying to do is get a distinct count of account numbers within a rolling period. My actual take is rather large but i've created a smaller-like version below. Please reference this table.








Account
Date

1
1/1/08

2
1/2/08

3
1/2/08

2
2/8/08

4
2/9/08

1
2/15/08

1
3/5/08

5
3/6/08

4
3/9/08

3
3/10/08

1
4/1/08

5
4/9/08

2
4/15/08

3
4/26/08

1
5/3/08

2
5/15/08

3
5/29/08

6
5/30/08

Let's say i want to return distinct count of accounts within a 2-month rolling period meaning in February, i'd get a distinct count for accounts in January & February, then in March i'd get a distinct count for February & March, then in April i'd get it for March & April, and so on... my results table would like the table below:








Account
Month

3
1

4
2

5
3

5
4

5
5

I had asked this before but it was a summing equation and not a unique count. I've tried to play with the summing equation to kind of make it work, but i'm starting to get a headache. It's probably so simple!

Here's my previous post: http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=2289509