need help with creating a certain query

[tosho]

Good evening, I have a question of how to pull all the customers that made 4 or more purchases in 60 days.
my table contains


customer number
purchase order number(unique for each purchase)
purchase date (covering 2 years).

I would truly appreciate your help.

Thank you!

[June7]

In 60 days from when - today or any 60 day period for the 2 years? Don't think latter will be easy.

[tosho]

I know it's confusing, but there is no period, if customer purchased something, did he purchased 3 or more items since his last purchase in 60 consecutive days.

[June7]

I was right, too tricky for me to tackle. Requires calculating the number of purchases that follow each purchase for the subsequent 60 days, a 'rolling' interval. Evaluating data in related records is not easy. Here is a fairly simplistic example of getting data from another record http://allenbrowne.com/subquery-01.html for calculating with the current record. So for each purchase date need to check if 3 more purchases within 60 days. The clue might be within Allen Browne's tutorial but too tired right now to think it through. VBA might be easier.

[recyan]

Is it that, if a customer made a purchase today, you want to find out if 3 or more purchases have been made in the past 60 days from today by the Customer.

Thanks