You share your db with customers?? Or is this web based?
If you're sharing, know that there is little you can do do prevent the db from being examined to discover how to undo whatever you decide to do. So if the invisible stuff is business sensitive or private, better come up with some other method, for which there are no doubt several possibilities.
Plus, the open even would be OK if the data that has to be examined (such as user name or level) is not part of the form. If it is, you'll have to use the Load event.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.