Because when I backup database or import into the new course, I only get database structure, but not the entries or the files which were into original database.
Thank you
If you backup/restore with user info you should get the entries and files.
Another option is to export then import all of your entries. Please see the documentation Using Database for more details.
I've just been trying to get a copy of a database (entries included). I has (wrongly) assumed that duplicating the database would suffice. It clearly did not. So the word 'duplicate' does not relate here.
Then I tried importing the database into the same course - this did not work.
Then I tried backing up the database and restoring it into the same course. Thankfully this worked but why should it take a backup and restore of a database to get a copy of it? Surely duplicating (making a copy) of the database should suffice?
If the academic in charge of this particular Moodle course is a low confidence user, they will panic if they know they've got to backup and restore a database every time they want to make a copy of it.
As a matter of fact the duplicate option does backup/restore but without user data. So it's really just terminology. Still I agree that it may be somewhat intimidating for some. This may be a viable usability issue with respect to all modules and it may be worthwhile to open a tracker issue for it if not already exists.