Consider the following schema:

AUTHORS (SSN, LastName, FirstName, Address, City, State)
PUBLISHERS (PubName, Address, City, State)
SALES (StoreName, TitleID, Qty)
TITLEAUTHOR (SSN, TitleID, RoyaltyPercent)
TITLES (TitleID, Title, Type, PubName, Price, PubDate)
STORES (StoreName, Address, City, State)

1. Write relational algebra expressions for each of the following:
   a. The names of stores that have not sold books.
   b. The names of all publishers in Chicago that publish books that cost 
      less than $10.00.
   c. The name and address of all stores as well as the title ID's of books 
      they have sold. Include stores that have not sold books.

2. Write SQL statements in each of the following cases:
   a. You have been asked to populate the NEWRELEASES table below. New 
      releases are books published in the current calendar year (assume 2001).
                 NEWRELEASE (TitleID, Title, Type, Price)
   b. All of Addison-Wesley's Biology books have been incorrectly classified 
      as Biochemistry. Addison-Wesley does not publish Biochemistry books. 
      Correct this error.
   c. Use a subquery to produce the names and addresses of publishers that 
      publish books that cost less than $10.00.
   d. List the name, and address of all stores in Illinois, as well as 
      titleID, and quantity of books sold by these stores. Include stores that 
      have had no sales. Order the result by name. 

3. You have been asked to revisit the schema above to accommodate a 
   SALESEMPLOYEE entity. This entity is intended to represent the sales staff 
   of publishers. The proposed attributes are SSN, Name, Commission, and 
   SalesCertification.
   Note: Some publishers do not have a sales force. Some sales persons have 
   multiple certifications (i.e. science, music, etc.).  
   a. Examine the proposed attributes and identify any composite attributes. 
      Define the atomic components of each composite attribute identified. 
   b. Examine the proposed attributes and identify any multi-valued attributes.
   c. Given your findings for a) and b), derive relational table(s).