Database Reference
In-Depth Information
4
THE RELATIONAL MODEL 3:
ADVANCED TOPICS
CHAPTER
LEARNING OBJECTIVES
Define, describe, and use views
Use indexes to improve database performance
Examine the security features of a DBMS
Discuss entity, referential, and legal-values integrity
Make changes to the structure of a relational database
Define and use the system catalog
Understand the use of stored procedures, triggers, and data macros
INTRODUCTION
In Chapter 3, you used SQL to define and manipulate table data. In this chapter, you will investigate some other aspects of
the relational model. You will learn about views, which represent a way of giving each user his or her own view of the data
in a database. You will examine indexes and use them to improve database performance. You also will investigate the fea-
tures of a DBMS that provide security. You then will learn about important integrity rules and examine ways to change the
structure of a database. You will use the system catalog found in many relational DBMSs to provide users with information
about the structure of a database. You will examine the use of stored procedures and triggers. Finally, you will see how
Access 2010 provides the functionality of triggers using data macros.
NOTE
In this chapter, concepts are introduced using SQL and followed by the method you would use to accomplish the same
task in Access 2010. Unless otherwise specified, the SQL commands in this chapter function in Oracle and MySQL exactly
as indicated.
NOTE
If you plan to work through the examples in this chapter using a computer, you should use a copy of the original
Premiere Products database because the version of the database used in this chapter does not include the changes made
in Chapter 3.
VIEWS
Most DBMSs support the creation of views. A view is an application program
s picture
of the database. An individual can use a view to create reports, charts, and other objects using database data.
In many cases, an individual can use a view to examine table data as well. Because a view is usually less
'
s or an individual user
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