Im bad at designing databases...and i am not sure it this would work:
Loaner {Name, Book_Owned} FOREIGN KEY (Book_Owned) REFERENCES Book (Book_ID)); Book {Book_ID, Author, Title, Publisher, Year, Avaliable(true/false} User {Name, Email, Book_Borrowed} FOREIGN KEY (Book_Borrowed) REFERENCES Book (Book_ID));
Any help will be much appreciated!