But your model is obviously wrong, because you can't find out the borrowing status of every book. For example, book database technology, there are five books in the library, so which one is marked by your "status" attribute?
In the actual library system, the relationship between borrowers and books is 1, that is, a borrower can borrow multiple books at the same time, but a book can only be lent to one borrower at the same time. Books have no inventory attribute, because they are not bookstores. Every book in the library has a unique logo, and even several identical books have different book numbers (different serial numbers are added after the library classification logo). This can ensure that every book can be tracked and the borrowing situation can be queried.