图书馆管理系统：library management system

Basic functions: 
Users can 
(view)
- personal information  (done)
- view all book information 
- view loan books  (done)
- view borrow history  (done)
- begin search
- get recommandation

(operate)
- check out books
- return books
- modified password

(front page actions)
- register a new account
- login  (done)
- log out

(administrator)
- add book info
- delete book info 
- query book 
- modify book info 


-----physical model
user(user_id, user_name, email， password)
book(book_id,  user_id(can null ), title, publisher, author, publish_year, tag,ISBN, call_number)
history(user_id, book_id, borrow_time, return_time)
loan(user_id, book_id,borrow_time)
tag
author
publisher
publish_year


---entity:  
user(user_id, user_name, email， password)

book(book_id, user_id, ISBN, call_number, title, publisher, author, publish_year, tag)

---relationship:

borrow: basket & book  one to many 
borrow(basket_id,  book_no,  borrow_time)

history:  user & book  one to many
history(user_id, book_no, title, borrow_time, return_time)