Check your Specific Manual, for the Sansa e200:
Ignoring Directories During Database Initialization
You may have directories on your player whose contents should not be added to the database. Placing a file named database.ignore in a directory will exclude the
that directory and all its subdirectories from scanning their tags and adding them to the database. This will speed up the database initialization.
If a subdirectory of an 'ignored' directory should still be scanned, place a file named database.unignore in it. The files in that directory and its subdirectories will be scanned and added to the database.
BTW, I don't use the Database, I play everything from Folders.