Using the schema of the tables on the next page, write relational algebra expressions for the following queries.

1 List the name and rating of the products that do not use Windows system.

2 List the user IDs and types of users that have permission to use Unix products. 

3 List the product IDs of products that are either Unix systems or have Type X users permitted to use them. 

4 List the name and rating of the product with the highest cost. 

5 List the ID of the user with the most total hours across all products (highest sum of hours). 

6 Insert a new user with the following information: 

                                                                         ID: 890              Password:           RST Type: Z Referred: 123 

7 Remove all products that have no users permitted to use it. 

8 Double the cost of the system with the highest rating

 

users userID password type referred 123 ABC X 234 DEF Y 345 GHI Z 456 ABC Z 567 JKL Y 678 MNO X 789 DEF X products productID 11 22 33 44 55 66 77 123 123 234 234 567 345 name rating system Alpha 1 Win Beta 2 Gamma 1 Delta 3 Epsilon 1 Zeta 2 Eta Unix Win Win Unix Mac Win cost 1000 2000 1500 1250 2500 1000 750 permissions userID 123 123 234 234 234 345 345 345 456 456 456 567 567 678 productID 11 22 33 44 55 66 77 11 22 33 44 55 66 77 hours 80 90 100 70 50 80 40 60 120 110 90 100 60 70