Please ask yours questions on English - other we may not full understand what you mean.
Create alone Database for Booklibrary - not full good. Now for yours security - responsible - Joomla. Otere you sef will responsible for that
Please chck below link how you may do that, and you may do that, but for Book Librrary you will need go through all ots file and check how we do access to Database - and check that
Or yu may ask for us custom version with some like that feature