calculate the Average of certain records

[mazides]

i use access 2007and i have a table with customer details and their purchases. I need a query tocalculate the average value of the last 5 purchases per customer, irrespectiveof the day those purchases took place. That is, one customer may have made hislast 5 purchases between lets say 15/09/13 and 25/09/13, while another may havemade them one month earlier.

[June7]

Check out the TOP parameter http://allenbrowne.com/subquery-01.html#TopN