We want to develop a database for a bookstore that satisfies the following requirements:

$$ This database keeps information of books and readers. Each book has a unique book ID and a title. Each book is assigned to one and only one category, such as Science, Business, History, etc.

$$ There are many rooms in the bookstore. Each room is labeled with a room name. One room can store one or many categories of books. One category of books may also be stored in multiple rooms if the number of books in the same category is too large.

$$ Each room has many bookshelves identified by bookshelf IDs. All books are stored on the bookshelves. Each bookshelf is labeled with a shelf name. This database should allow readers to easily find which bookshelf a book is located on$.$

$$ This database should also store reader information, including reader ID$,$ name, home address, email address, and phone number.

$$ We should also keep track of the books borrowed by readers. One reader may checkout many books and return a book within two weeks. It is possible that one reader does not checkout any book.

Please answer the following questions:

$1.$ Draw an ER diagram to represent this database.

$2.$ Refine the ER diagram and derive a relational schema based on your refined ER diagram