If they install the demo version after full version, then they have also over-written their entire database with the demo version if they were single-user system. If they were multi-user version, then their production database is still fully intact. The demo version would be using the local database leaving full version DB intact. To get a demo version, they have to explicitly ask me for it as well as download instructions. Our customer base is very specific and we know all of them as well as their "mentality" so to speak. But yes you are absolutely correct that this can be disasterous if installed in the wrong order.

In our full version, to help prevent the situation you brought up, we include the ability to switch the DB to a training DB where we do NOT prevent access to anything. IN the training DB they are free to try to mess up anything they want without affecting the live DB.

>The way shown in your example is a little bit dangerous.
>If customer would uninstall full version and next install the demo version his data would be deleted. One can not assume that application user always acts in logical way.
>IMHO the better way is checking demo limit before executing an insert command.