RE: rolling group by

Dave,

I haven't worked with them much, yet, but if you are on 8.1.6, you might want to look into using the "analytic" functions and the STDDEV functions. Here is a snippet from the SQL manual:

<<<Start>>>

Analytic Functions

Analytic functions compute an aggregate value based on a group of rows. The group of rows is called a window and is defined by the analytic clause. For each row, a "sliding" window of rows is defined. The window determines the range of rows used to perform the calculations for the "current row". Window sizes can be based on either a physical number of rows or a logical interval such as time.

Analytic functions are the last set of operations performed in a query except for the final ORDER BY clause. All joins and all WHERE, GROUP BY, and HAVING clauses are completed before the analytic functions are processed. Therefore, analytic functions can appear only in the select list or ORDER BY clause.

Analytic functions are commonly used to compute cumulative, moving, centered, and reporting aggregates.
<<<End>>>

If prior to 8.1.6, you might try it using STDDEV and a self join with criteria setting the boundaries:

select M1.Tdate, stddev(m2.measure) Received on Wed Sep 20 2000 - 20:30:32 CDT