List of books (title, ISBN, author, unit price, publishing house) Main code: ISBN.
Reader list (library card number, name, gender, unit, category number) main code: library card number, external code: category number.
The main code of the library slip (library card number, book number, end date and book return date): library card number+book number+end date.
Foreign code: library card number, book number
Loan authority table (category number, name, maximum loan amount and loan term) Primary code: category number.
Draw an E-R diagram accordingly, and pay attention to one-to-many and many-to-many directions.