Hi pietlinden, for one username it should look like this.

For example April's rolling average is 9+13+3/3. May's is 7+9+13/3, June's is 12+7+9/3

username---move_in_date-----------cnt_lead_id------Rolling 3 month Avg

DebiV--------2014-02-01 00:00:00------------3----------NULL

DebiV--------2014-03-01 00:00:00------------13---------NULL

DebiV--------2014-04-01 00:00:00------------9----------8

DebiV--------2014-05-01 00:00:00------------7----------9

DebiV--------2014-06-01 00:00:00------------12---------9

DebiV--------2014-07-01 00:00:00------------8----------9

DebiV--------2014-08-01 00:00:00------------9----------9

DebiV--------2014-09-01 00:00:00------------11---------9

DebiV--------2014-10-01 00:00:00------------8----------9

DebiV--------2014-11-01 00:00:00------------4----------7

DebiV--------2014-12-01 00:00:00------------4----------5

I rounded down, in the event of a decimal.

I have Itzik Ben-Gan's 2008 querying book , but nothing in index for 'moving', 'rolling', or under 'average' for same.