I tried asking this at the MSDN website and didn't get an answer at all...I was hoping someone here could help.

If I indicate that SQL Server Express is to be a pre-requisite for my application, how does the installer interpret this? For example:

If end user A already has SQL Server Express installed when they install my application, does my application create a new instance of a SQL Express Server or does it use the one that's already available? What about if there are multiple instances installed already or if the instance name I specified is already taken?

If end user B already has SQL Server Express installed and my application uses the installation they already have, what happens if there is a database name conflict? In other words, they already have a database with the same name that my application uses in that instance?

Finally, if end user C does not have SQL Server Express installed, but has a retail version of SQL Server installed, will my application use the retail version or install the express version along with it?

Sorry for the odd questions but I have yet to find an answer to these questions and I'd rather not spend hours developing an application and run into a surprise.

__avd commented: Nice question. +12