1) Welcome to the Party!
2) While I am certain that you have a good reason to ask that question, honestly it makes me nervous that you would ask it. This is because anyone qualified to work directly with the mysql files themselves would unquestionably know how to find them. Anyone who does not know where to find them, as a solid rule, should NOT be touching them. Direct interaction with mysql tables is a strict nono. Backups are managed through the application. Table modifications also. So the question is: WHY do you want to know where they are?
3) when you post, please post your entire configuration including (but not limited to) your installation method and vicidial version with build.
this IS a requirement for posting along with reading the stickies (at the top of each forum) and the manager's manual (available on EFLO.net, both free and paid versions)
You should also post: Asterisk version, telephony hardware (model number is helpful here), cluster information if you have one, and whether any other software is installed in the box. If your installation method is "from scratch" you must post your operating system and should also post the .iso version from which you installed your original operating system.
If this is a "Cloud" or "Virtual" server, please note the technology involved along with the version of that techology (ie: VMware Server Version 2.0.2). If it is not, merely stating the Motherboard model # and CPU would be helpful.
Similar to This:
Vicibox X.X from .iso | Vicidial X.X.X-XXX Build XXXXXX-XXXX | Asterisk X.X.X | Single Server | No Digium/Sangoma Hardware | No Extra Software After Installation | Intel DG35EC | Core2Quad Q6600
If you are, indeed, working from the Demo, they will likely be in /var/lib/mysql