How query only the THREE most recent records in a table

if you have an autonumber field this will do it

select top 3 * from TableName
Order by [autonumberfield name] desc

Once again I didn't explain the challenge very well.

I need to select the most recent three records from tblOpenOrders where Part_No = Forms!frmOpenOrders!txtPart_No

What should the SQL be for this?

And the records in tblOpenOrders do have an autonumber record ID number.