I hope someone can assist me?

I am looking for a solution to an excel query thats been puzzling me for a few days now. This is what im looking to do?

I have an online quote system, which my users use to create/update customer quotes. Each time they update or create a new quote, this is date and time-stamped. It has a sql/access back-end, so the updates are stored within another table.

I want to be able to create a chart/pivot table, which will display the updates for each user within the last 30 days. I can pull the data from Access, so i have two columns with username and update date/time.

I have managed to get all updates by all users displayed in a chart, but I just want to see the updates for the last 30 days.

Is it a formula that i need to create?

Any help/pointers would be very much appreciated!