Milin,<br>
Here, as with any solution, you'll want to clearly define your objectives. Ie, what do you mean by 'accessed'? Elizabeth's point is very good, and going further--what if the user hit's the navigation buttons back and forth while browsing the the form--a record may get 10 hits, and it might not even be the one the user was really after. I'd suggest using a 'Search' button, and open the form with the recordsource (should be a query or dynamic sql) with no records, ie. "WHERE CustomerID = 0". Turn off the 'recordselectors', 'navigation buttons' properties, etc. This is how you lock things down and get control of what users are doing. Then in the search button event, use whatever fields you allow to search on, and you set the recordsource sql. A found record updates the field as JimConrad suggested.<br>
This is my suggestion for most Access forms anyway. it's easy to turn off the navigation buttons, etc, and to create your own 'next record' buttons, etc. The advantage is that *you* have control over these actions, and can track these things you need to track with accuracy. Yes, I'm a control-freak like that

It'll keep headaches to a minimum when you know exactly what your users are allowed to do with regard to record navigation.<br>
--Jim