took this query from stackoverflow and substituted my values. But, there's no concept of 3 month rolling average.
;WITH cte (rn, username, move_in_date, Cnt_Lead_id) AS (
SELECT
rn = ROW_NUMBER() OVER (ORDER BY move_in_date),
username,
move_in_date,
Cnt_Lead_id
FROM [dbo].[countHistory]
)
SELECT
username,
move_in_date,
Cnt_Lead_id,
movagv = (
SELECT AVG(Cnt_Lead_id)
FROM cte AS inner_ref
WHERE inner_ref.rn BETWEEN outer_ref.rn-3 AND outer_ref.rn
)
FROM cte AS outer_ref
ORDER BY username, move_in_date
If you run this against the sampletable DDL you'll see it doesn't do 3 month rolling.