Hi folks

My partner is an alternative therapist and I have somewhat foolishly promised to write a custom CRM type application for her. Since I've been involved in database design & programming for over 10 years, the design and implementation in itself shouldn't be a problem, except for one minor detail - she wants the whole application, including database, to be installed on a USB key rather than on her laptop.

The USB key is 4 Gb so size isn't a huge problem, but since my background is mainly Sql Server, which is not portable in that way, I was wondering if anyone has any recommendations?

The criteria are:

• Must be accessible via C# or at a pinch Java (would be a good learning exercise) without having to jump through too many hoops.
• Must be possible to secure, as Db will contain peoples names, contact details and sensitive information about medical problems etc
• Must be fully portable, "hot pluggable" i.e. the whole application can run off a USB key, although it's permissible to install runtimes to the PC or laptop
• Out of preference the Db app should be fairly slimline, i.e with as little metadata and unnecessary bumf taking up space on the stick as possible.

Any ideas? At the moment I'm considering using encrypted XML/XSLT files and XPath, but I would really prefer to use SQL. I remember "in the old days" you used to be able to build an Access Db into an application and the target machine wouldn't need Access installed, just the Jet libraries and possibly MDAC... but nowadays the desktop database solutions seem to require major installs before you can use them!!

Thanks in advance!!

Given the latest government faux pas involving USB "memory sticks" it might not be a good idea

Personally I would look at a stand alone application written in C/C++ or Delphi (or similar) where there are no need for any runtime libraries other than standard windows ones. You could use bespoke datafiles with custom encryption or Access mdb/mde files plus MDAC.

Access is your best bet - as long as you have a standard Windows installation, you don't actually need Access to be able to open mdb or mde files. Just JET, which is part of MDAC. In Access (or XML), you can encrypt part of the data using your choice of algorithm (System.Cryptography in C#, if memory serves) and then write out the bytes in base 64.

You could use SQL Server pretty easily, depending on what "hot" means, exactly. The USB memory should attach as a drive, and get a specific letter. So you can use a file path on that drive to create your database. Then attach and detach it when you want to plug the USB into the computer, and take it on the run.

Given the somewhat large scope of the project, I'd highly recommend using the skills you've already got, rather than learning a new language from scratch. C# is amazingly expressive, possibly the best all around programming language there is right now.