From: cru on 17 Jan 2010 01:13 I am trying to find easier way to calculate prior 3 mo average. Currently, I am doing the manual calculation in Excel after importing from Access. I would like to calculate in Access. In the table, I want to calculate period 12/31/2009 where I need the 3mo average of the prior 3 mo count. I wonder if there is a function that can say for current month what is the prior 2 mo avg (counting the current period) PERIOD COUNT 3-MO AVG 10/31/2009 1000 11/30/2009 2000 12/31/2009 3000 2000 Your help is appreciated! Cru From: Allen Browne on 17 Jan 2010 02:14 Use a subquery to get the 3-month average. This kind of thing: SELECT [Period], [Count], (SELECT Average([Count] AS AvgCount FROM Table1 AS Dupe WHERE Dupe.[PERIOD] Between DateAdd(m, -2,Table1.[Period]+1) And Table1.[Period])) AS Avg3Month FROM Table1; If subqueries are new, here's an intro: http://allenbrowne.com/subquery-01.html Note that it would be wise to avoid reserved names like Count for your fields. Here's a list: http://allenbrowne.com/AppIssueBadWord.html -- Allen Browne - Microsoft MVP. Perth, Western Australia Tips for Access users - http://allenbrowne.com/tips.html Reply to group, rather than allenbrowne at mvps dot org. "cru" wrote in message news:07D0C09B-954E-4633-9EF6-E0B9ADE480AC(a)microsoft.com...> I am trying to find easier way to calculate prior 3 mo average. > Currently, I > am doing the manual calculation in Excel after importing from Access. I > would like to calculate in Access. > > In the table, I want to calculate period 12/31/2009 where I need the 3mo > average of the prior 3 mo count. I wonder if there is a function that can > say for current month what is the prior 2 mo avg (counting the current > period) > > PERIOD COUNT 3-MO AVG > 10/31/2009 1000 > 11/30/2009 2000 > 12/31/2009 3000 2000 > > Your help is appreciated! > Cru  |  Pages: 1 Prev: How do I left justify a dateNext: Variable as FieldName to populate a combobox