Hi Everyone!

In the previous question (Please refer to: SQL Keeping count of occurrences) I needed to count the number of occurrences of a variable.

The code provided was as follows:

SELECT 

    [Date], Code, 

    [Count] = COUNT(*) OVER (PARTITION BY Code ORDER BY [Date] ROWS UNBOUNDED PRECEDING)

FROM dbo.YourTable

ORDER BY [Date];

However, now I need to introduce an improvement to that code:

Let's say that I have the following table:

   Date          | Code

   ------------------------

   2010/01/01    | 25

   2010/01/01    | 22

   2010/01/01    | 23

   2010/01/01    | 25

   2010/01/02    | 23

   2010/01/02    | 23

   2010/01/03    | 23

   2010/01/04    | 23

   2010/01/05    | 23

   2010/01/06    | 23

   2010/01/07    | 23

   .....

   2013/03/02    | 21

Now, I need to count the number of occurrences in a specific period of time. The desired output would be as follows (supposing a time frame of n=2 days, for 

the sake of simplicity)

    Date         | Code  |  Occurrences

   ------------------------------------

   2010/01/01    | 25    |      1

   2010/01/01    | 22    |      1

   2010/01/01    | 23    |      1

   2010/01/01    | 25    |      2

   2010/01/02    | 23    |      2

   2010/01/02    | 23    |      3

   2010/01/03    | 23    |      3 -> We are not considering the occurence in 2011/01/01 as it is out of the scope now

   2010/01/04    | 23    |      2 -> Considers only occurrences in 01/03 and 01/04 

   2010/01/05    | 23    |      2

   2010/01/06    | 23    |      2

   2010/01/07    | 23    |      2

   .....

   2013/03/02    |  21   |      1

That is, I need to know how many times the code 'x' has appeared in my table in the last 'n' months.

This is run in SQL Server 2012.

Thank you in advance.