Homework assignment #4
CS 643, Spring 2002
Due: Wednesday, March 6, 2002
Total points: 100

In class, You'll be asked to perform the following exercises with the tables in the HR schema. Save all transactions in "transaction2.sql". Submit the file along with your homework report. Make sure that you give proper documentation of the transactions. This section can be shared by two students.

1. Assume two users are accessing the database at the same time. Write two transactions to illustrate nonrepeatable read. 
2. Assume two users are accessing the database at the same time. Write two transactions to illustrate phantom read. 
3. Assume two users are accessing the database at the same time. Write two transactions to illustrate both nonrepeatable read and phantom read are prevented. Observe how Oracle handle the problem. 
4. Assume two users are accessing the database at the same time. Write two transactions to illustrate deadlock. Observe how Oracle handle the problem. 

For the homework assignment, you're asked to answer the following questions. It is very important that you use concrete examples to illustrate the concepts. This section needs to be individual work.

1. Add proper documentation to the above transactions to explain the purpose of transactions, the potential problems, and how Oracle handle the problems.
2. Exercise 19.15.
3. Exercise 19.18 (b), (d), & (e).
4. Exercise 19.19 (b), (d), & (e).
5. Exercise 19.21.