For the bookstore database, write expressions of relational algebra to answer the following queries:

1.) All possible pairs of books (Bname). (A pair should be listed only once).

itabase 3: Assume a book store has a mail-order database with the following schema of relations: (Primary keys are derlined. Meaning of each attribute is self-explanatory by its name.) Employees (ENO, Ename, Hire_Date); Books (ISBN, Bname, Quantity, Price); Customers (CNO, Cname, Street, Zip, Phone); Orders (ONO, CNO, ENO, Received, Shipped); Orderline (ONO, ISBN, Qty); Zipcodes (Zip, City, State)