I need help answering these questions. I\'ve gotten the first one and am having

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I need help answering these questions. I've gotten the first one and am having trouble with ones after. If I see how a few are done I will be able to better understand it.

Consider a library database with the following schema (where primary keys are bolded):

Book(bookID, ISBN, title, author, publish-year, category)

Member(memberID, lastname, firstname, address, phone-number, limit)

CurrentLoan(memberID, bookID, loan-date, due-date)

History(memberID, bookID, loan-date, return-date)

Members can borrow books from the library. The number of books they can borrow is limited by the “limit” field of the Member relation. The category of a book includes fiction, non-fiction, children’s and reference. The CurrentLoan table represents the information about books that are currently checked out. When the book is returned to the library, the record will be removed from CurrentLoad relation, and will be inserted into History relation with the return-date. A library may have more than one copy of the same book, in which case each copy has its own bookID, but all copies share the same ISBN. Express each of the following tasks in relational algebra.

(5 pts) Find the ISBN and title of all the books authored Arthur Miller.

(8 pts) List the bookID and title of all the books that are currently checked out by John Smith. Do not use any natural join in this query.

(8 pts) Find the first name and last name of the members who are either currently borrowing book “Da Vinci Code” or have borrowed it in the past.

(6 pts) Find the memberID, first name, and last name of the members who have never borrowed any books.

(8 pts) List the first and last names of members who have borrowed (either currently or in the past) all the books in the library that are authored by Arthur Miller. If some books authored by Arthur Miller have multiple copies, he or she must have borrowed at least one copy of each of Arthur Miller’s books.

(5 pts) Find the total number of books for each category (write a single query for this question).

Explanation / Answer

Given relation is:
Book(bookID, ISBN, title, author, publish-year, category)
Member(memberID, lastname, firstname, address, phone-number, limit)
CurrentLoan(memberID, bookID, loan-date, due-date)
History(memberID, bookID, loan-date, return-date)

Find the ISBN and title of all the books authored Arthur Miller?

select ISBN, title from Book where author='Arthur Miller';

List the bookID and title of all the books that are currently checked out by John Smith. Do not use any natural join in this query.

select B.bookID, B.title from Book B,Member M,CurrentLoan C where B.bookID=C.bookID and M.memberID=C.memberID and M.firstname='John Smith';

Find the first name and last name of the members who are either currently borrowing book “Da Vinci Code” or have borrowed it in the past.

select M.firstname, M.lastname from Book B,Member M,CurrentLoan C where B.bookID=C.bookID and M.memberID=C.memberID and B.title='Da Vinci Code';

Find the total number of books for each category ?
select isbn, booktitle, sum(case when status='available' then 1 else 0 end) as avail, count(*) as total
from Book;
group by isbn, booktitle

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