Answer to Question #232198 in Databases | SQL | Oracle | MS Access for Tebza

Question

Assuming the following relations from a customer database, write relational algebra expression for each statement using symbolic notations. Customer (cid, cname, rating, salary) Item (iid, iname, type) Order (cid, iid, day, qty) 2.1.1 Find the names of customers who have ordered item with id 087. (2) 2.1.2 Find the names of customers who have ordered a television i.e., an item of type television. (3) 2.2 Consider the following relations from a Richfield database. Write relational algebra expression for each statement using symbolic notations. Books (bid, title, publisher, year) Students (sid, sname, major, age) Authors (aid, aname, aaddress) Borrows (bid, sid, date)

Answer 1

2.1.1 Find the names of customers who have ordered item with id 087.

Customer ⋈θ customer.cid=order.cid Order

2.1.2 Find the names of customers who have ordered a television i.e., an item of type television.

Customer ⋈θ customer.cid=order.cid Order (Order order.iid=item.iid Item)