1. Within relational model systems on both mainframes and personal computers, the main mechanism for increasing the efficiency with which data is retrieved from the database is the ____________________.

2. What are the advantages of having views only contain the fields required by a given user?

3. Under which conditions should you create an index on a field (or combination of fields)?

4. Explain what is meant by a null value. Is a null value the same as a value of zero?

5. What is the difference between entity integrity and referential integrity?

6. Discuss what you can do if you need to change a tables structure in ways that are beyond the capabilities of your DBMS.