mastering oracle 8i

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ORACLE8i
™
Robert G. Freeman
Mark D. Blomberg
San Francisco • London
MASTERING
™
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While this book was being written, the cowardly attacks on
the World Trade Center, the Pentagon, and in Pennsylvania
took place. Thus, this book is dedicated to all those who
died there and in other terrorist tragedies throughout the

world. This is dedicated to all the children who lost parents,
the wives who lost husbands, and the husbands who lost
wives. It is dedicated to the grieving families and friends
and to the hope of peace, but also to the hope of justice for
those who feel that terror and destruction are reasonable
alternatives to peace and dialogue.
As always, this work is dedicated to my family—my father
and my mother, my brother and sisters, and most of all, my
wife and children, who sacrifice their time with me in the
writing endeavors that I take on.
—Robert G. Freeman
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ACKNOWLEDGMENTS
T
here are numerous individuals who deserve recognition, and if we could put
them all on the front cover, we would. Thanks to Richard Basile and Shagun
Tyagi, whose names do not appear on the front cover but who contributed
to the original content of this book.
Thanks to my co-author Mark Blomberg, who really worked hard to make this
happen.
Thanks, of course, to those who helped make this book what it is. To my friend Jeff
Kellum, who put me in contact with everyone else—including Richard Mills, our sup-
portive associate publisher. To the wonderful editing staff of this book, Leslie Light,
Marilyn Smith, and Carol Henry. Many thanks, as well, to technical editor Ashok
Hanumanth. In addition, thanks to Christine McGeever, acquisitions and develop-
ment editor, who helped get the book off the ground. The CD team and Dan Mum-
mert did a fine job of assembling the CD material. To the production staff, including
talented compositor Adrian Woolhouse, thanks for making the book look great.

Of course, there are countless people who helped and didn’t even know it. Special
thanks to Steve Adams, Tim Stippler, Charles Pack, Mike Ault, Pete Sharman, John B.,
KG, and numerous other awesome people in the Oracle community!
Special thanks to the folks I work with: Nancy Von Dolteren, Yang Jiang, Don
Mongeon, Bob Just, Bill Barker, Wendy Hausler, John King, Bill Sullivan, Gunjan
Nath, Richard McClain, Nirupam Majumdar, and Maritza Gonzalez. You are all great!
Thanks to those who provided moral support (and allowed me to not hold boards for
board breaking while I was writing this!): Mrs. Skutnik, Mr. Alfaro, and all those at
Master Clark’s Karate America in Jacksonville. Thanks to our many friends, who
always support us.
Finally, thanks to my wife and my five kids, who came into my work area about
once a week just to refresh their memories of what I look like.
Robert Freeman
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I would like to take this opportunity to thank the staff at Sybex for all their hard
work through the long months of this project. The staff at Sybex were helpful,
resourceful, and most of all, knowledgeable.
I would also like to thank my wife and family for being tolerant of my absence and
not making the appropriate time to spend with them. So thank you to my wife Ann,
and daughters Rebecca and Dana.
Finally, I would like to thank Robert Freeman for bringing me into this venture and
giving me the opportunity to realize one of my personal goals.
To all involved, a truly grateful THANK YOU.
Mark D. Blomberg
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W

e want information… information ” Possibly you recognize these
words as the primary interest of a somewhat clandestine group, and as
told by a character called Number 2 to Patrick McGoohan’s character
Number 6 (in the old TV show The Prisoner). Indeed, in this day, infor-
mation is king, and the speedy, accurate, and reliable retrieval of this information is
paramount.
And if you wish to store and retrieve information quickly, Oracle’s flagship data-
base product is the way to go. Oracle Corporation currently “owns” the major share
of the large database market, which is one sign of the superiority of Oracle’s product.
The Oracle product is robust in features and very fast—but it can also be complicated
and expensive to run. As much as Oracle wishes to market its database product as
being easy to manage and install, the truth is that an experienced DBA is generally
needed for anything other than the most elemental installation and operation.
We hear often from aspiring or beginning DBAs wondering how they can join the
ranks of Oracle DBAs. Experience is undeniably one of the primary requirements for
DBA excellence. Yet, the need to acquire that experience also stands in the way of the
junior DBA’s advancement. This experience requirement has made senior DBAs some-
what scarce, and it’s also a principal reason for the good salaries offered to truly good
DBAs. In other words, you can’t just pick up a book, go through the motions, and
become a great DBA.
The bottom line for employers is that it’s best to start out with the best and brightest.
(“You can pay me now, or you can pay me later.”) If you’re investing millions in equip-
ment and software, then you want to invest in talent, as well, at the beginning. Once
you have a stable, well-designed system up and running, then you can bring on the
juniors to maintain it.
Getting one’s foot in the DBA door is difficult. What you can do, however, is
learn from each book you study. Realize that just knowing the commands and how
the processes work is not enough to become a good DBA. In addition, you need to
know about backup and recovery. You need to know about tuning the database and
tuning the SQL running in the database. You need to know how to ferret statistics out

of the database and how to interpret them. That’s what mastering Oracle database
administration, and this book, are about.
INTRODUCTION
“
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INTRODUCTION
xxviii
This text goes beyond basic administration tasks, though it covers those as well.
Within these pages you will find nuggets of our experience that might help you. We
hope that you will also take away from this book the fact that administration of an
Oracle database is a multifaceted job. Finally, remember that the best approach to
management of Oracle is a proactive one. Don’t sit and wait for problems to occur.
Is This Book for You?
We assume that the reader has fundamental knowledge of an Oracle database. If you are
a beginning DBA with little or no understanding of Oracle, you should carefully read
Chapter 1 before going further. In addition, we strongly suggest that you read a selec-
tion of the following books; these are in order from basic to advanced skills coverage:
• Oracle DBA 101 by Marlene L. Theriault, et al
• The Sybex Oracle Certified Professional (OCP) series of certification study
guides, including
• OCP: Oracle8i DBA SQL and PL/SQL Study Guide, 0-7821-2682-0
(Sybex, 2000)
• OCP: Oracle8i DBA Architecture & Administration and Backup & Recovery Study
Guide, 0-7821-2683-9 (Sybex, 2001)
• OCP: Oracle8i DBA Performance Tuning and Network Administration Study
Guide, 0-7821-2684-7 (Sybex, 2000)
Though this set of books is designed primarily for those working toward the
Oracle OCP exams, the study guides really are a good introduction to the Oracle

product.
• Oracle8i Networking 101 by Marlene L. Theriault
• Oracle8i Administration and Management by Michael R. Ault
If you are a beginning DBA and do not have direct access to the Oracle product,
you can download a copy of Oracle from Technet (www.technet.com), the Oracle web-
site that contains demonstration copies of Oracle software. Technet also contains
code samples and Oracle documentation.
Following are some other beneficial websites that you might use in your quest to
master the Oracle database product:
www.revealnet.com This website provides information on the product
offerings of RevealNet Labs (Quest Software), which develops state-of-the-art tech-
nical knowledge bases and development/administration tools for Oracle, DB2,
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xxix
and SQL Server. The site also includes the Oracle DBA Pipelines, a forum for
Oracle database administrators to meet and share ideas and ask for help. The syn-
tax diagrams throughout this book and in Appendix E (on the CD) were produced
using the RevealNet Knowledge Base for Oracle Administration.
www.oracle.com This is the main page of Oracle Corporation’s website.
Here you can find information on Oracle and download certain products.
education.oracle.com This is Oracle Corporation’s education site, which
offers information on Oracle training courses and becoming an Oracle Certified
Professional.
metalink.oracle.com Metalink is the online website for Oracle users. If
you are an Oracle support customer, you will have access to this site. Use it to
search out help with existing Oracle bugs, to find Oracle documents, and to
access Oracle forums on various subjects.
www.ixora.com.au The Ixora site provides a great wealth of Unix-related

Oracle internal knowledge, as well as scripts that you can use to monitor the
health of your database.
What You Need to Know
As you pick up this book, understand that we have not devoted a great number of its
pages to examining every fundamental detail of the Oracle database environment.
You should already be comfortable with putting together SQL statements, and you
should know what SQL*Plus is.
Although the book as a whole is not designed for beginners, beginning DBAs will
find Chapter 1 to be a quick primer that may well be enough to help them on the way
to mastering Oracle8i database administration.
If you are a junior DBA, this book is right up your alley. You’ll be comfortable
already with what’s involved in starting and stopping the database and working with
simple queries. You’ll have some understanding of what the data dictionary is, and
perhaps even be familiar with parts of it. It’s our hope that you’ll eat this book up and
that it will give you the knowledge you need to become a truly great DBA.
If you’re already a master DBA, we hope this text will be a trusted reference, and
perhaps provide insight into some aspects of database administration that you want
to improve.
INTRODUCTION
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INTRODUCTION
xxx
Conventions Used in This Book
One of the themes you’ll find in this book is consistency. Within these pages we follow
a set of terminology standards that are in fairly common use in the Oracle community.
We suggest that you adopt these standards in your daily operations, as well.
Within the text, Oracle keywords are in uppercase (SELECT, INSERT, FROM,
V$PARAMETER, PARTITION BY HASH). Table and column names are in uppercase,

as well, to distinguish them from the surrounding text (the EMP table; the EMP NO
column).
In addition, the following elements appear in this book:
NOTE Notes like this will appear from time to time. Generally when we want add a
comment that pertains to a particular section, we will do so in a note.
TIP Tips like this are used to highlight particularly important procedures or processes.
WARNING Warnings are used in the text to keep you from destroying something
inadvertently. When a warning appears, make sure you read it carefully. We also use warn-
ings to point out bugs in the Oracle8i product that we know about.
How to Use This Book
You may find it easiest to read the chapters in order, but it’s not essential. One of our
goals was to make it possible for you to pick the text up and read any individual chap-
ter without having to study several other chapters first. We have grouped similar
chapters logically, but otherwise (with a few exceptions) the chapters do not particu-
larly “build” upon one another. To make it easier for you to move among the chap-
ters, we have included plenty of cross-references throughout the book.
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xxxi
Of course, you’ll get the most benefit from this book by putting the material to real
use. Take the examples and the generic routines we’ve provided and expand on them.
Add and subtract from them and incorporate them into your own database manage-
ment activities. Experiment and enjoy!
What’s On the CD
The CD is chock full of goodies!
First, you’ll find a complete electronic edition of the book.
All nine appendices, which are not in the printed book, are on the CD. You’ll find
the Quick Reference appendices especially helpful. They’re all in easy-to-search .PDF
format.

We’ve also provided some trial versions of products that can help you better man-
age your database. Note that these demos require that you purchase a license for con-
tinued use; please read the provided supporting documentation and respect the rights
of the vendors who were kind enough to provide these files. All of the following are
from RevealNet Labs (Quest Software), www.revealnet.com:
• The Formatter Plus tool, which will do a quick syntax check of your SQL. It
works on code that has no Oracle syntax errors and is compilable or executable
on Oracle, but it is more permissive than the PL/SQL compiler or SQL*Plus
environment.
• The RevealNet Knowledge Base for Oracle Administration, to help you find solu-
tions for your questions about Oracle database administration.
• The Active PL/SQL Knowledge Base combines a comprehensive PL/SQL refer-
ence with an extensive PL/SQL Code Library. It offers a valuable source of tech-
nical expertise and a substantial library of procedures and functions.
Also included on the CD is the Oracle8i table, index, and SGA sizing spreadsheet
discussed in Chapter 3 of the book, compliments of Mike Ault and TUSC.
NOTE For late-breaking information about the CD, including additional files and utili-
ties, see README.TXT in the root directory of the CD.
INTRODUCTION
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INTRODUCTION
xxxii
Come Visit Us
We hope that you will share with us your feelings about this book. Let us know what
has helped you, and what you might like to see in the next incarnation of this work.
You might well disagree with some things stated here—being a DBA is somewhat like
being an artist, and not everyone agrees on what makes a work of art. We hope that
you will communicate with us and let us know what you liked and what you didn’t.

We have set up a website, www.masteringoracle.com, where you’ll find a link to
e-mail Robert. There are also some links to the book’s errata and other nifty things!
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Oracle Essentials
PART
I
LEARN TO:
• Install Oracle
• Migrate to Oracle
• Create an Oracle database
• Use the Oracle data
dictionary
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CHAPTER 1
Elements of
Oracle Database
Management
FEATURING:
What is a DBA? 4
Introducing Oracle8i 5
Oracle internals 13
The physilogical Oracle 17
Fundamental Oracle principles 19
Environment settings 21
The Oracle SQL interface tools 22
Using Oracle SQL 29

Oracle PL/SQL 39
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elcome to Mastering Oracle8i. We hope you find this book useful in
your DBA endeavors. We’ve made every effort to fit as much priceless
information into this book as we could find, and hope you refer to
it daily.
This book was written as a reference for the working Oracle DBA. We assume most
of you already know Oracle well and want to explore Oracle8i in particular. And if
you’re new to Oracle, start right here. The pace might seem fast and furious, but
you’ll manage quite well.
Here in Chapter 1, we offer a broad view of Oracle and SQL fundamentals. We’ll
begin with a refresher on the DBA’s role. Then we’ll review some database theory and
Oracle history. Following that is a discussion of Oracle internals, the building blocks
you must master for successful database administration. Next up is a discussion of
SQL*Plus and other elements of the Oracle database interface. In addition, we will
briefly discuss the tools used to access the database, fundamental concepts of the SQL
language, and how to use SQL in the database. All of these introductory subjects are,
of course, covered in depth in later chapters.
What Is a DBA?
There seems to be an air of mystery surrounding database administrators and data-
base management. But really, being a DBA boils down to just a few basic qualities:
• Willingness to work long, sometimes hard hours
• Ability to ferret out the answers
• Determination to be the best
• The drive to succeed
• Knowledge of database administration
• Experience in database administration

New DBAs can make up for a lack of the last two qualities by concentrating on the
first four. As you gain knowledge and experience, you’ll find that you don’t need to
work so many long, hard hours quite as often as when you first started. You’ll make
fewer mistakes, and you’ll know where to look first for the answers—no ferrets required!
We aren’t trying to snowball you, though. There will always be users who call you
at midnight, needing your help to recover a database. But you’ll be up to the task.
With knowledge and experience comes a better DBA who can truly become a “lazy
DBA.” (In Chapter 15, which covers performance monitoring, you’ll find a definition
of a “lazy DBA”—and it’s not someone who just sits around.)
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5
Robert’s Rants: Stick to Your Guns
As DBA, you’re very much the heart of the database. If you fail, your database fails. Do
not be complacent with your database just because it’s performing well. Do not ease
up on vigilance against risks to your systems, including policies and procedures that are
not in the best interest of your database. Granted, there is a time to fight and a time to
lay low, but this is your job. The life of your database is your job.
Yes, I’m on a soapbox; this is my chance to rant. I’ve met many a DBA who rolled over
and gave up because a project manager ordered them to do this or do that. But don’t
forget that you are the DBA. Go on out and look at the top job-hunting web sites, and
count the number of DBA jobs out there. If you’re a DBA, you’re in high demand, so
you have the freedom to say no and stand by it. I’ve had more than a few encounters
with a manager trying to bully me into doing something I just wasn’t going to do. I’ve
simply told them to go fly a kite. I might even have mentioned something about my
black belt in karate, if they were particularly unpleasant.
Of course, please do make sure you can back up your point of view with some good
solid facts. In the end, when you’re proven right, you and your database will be better
for it, and so will the community using that database. The point is, if you know you’re

correct, don’t back down for a second. Compromise is fine, if it doesn’t compromise the
integrity of the database in your charge (or your own integrity). Someone may demand
your head, but it’s a sure bet that most of your company’s management knows the
value of your position—and if they don’t, they will soon find out.
Of course, if you end up getting fired, I didn’t say this and I’m not here.
Introducing Oracle8i
In this section we will briefly discuss some relational database theory and some Oracle
history. We will take an overview of Oracle8i, the latest and greatest version of Oracle,
and see how the Oracle database is both relational and object oriented.
TIP Already an expert on relational theory? Already know that ACID means something
else besides what you used to melt things in chemistry class? You can skip this section
altogether; go ahead and move on to “Internals.”
INTRODUCING ORACLE8i
Oracle Essentials
PART
I
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CHAPTER 1 • ELEMENTS OF ORACLE DATABASE MANAGEMENT
6
Oracle is a relational database geared to meet the information processing require-
ments of business. Its features include support for all of the following:
• A large number of users and high-concurrency activity.
• Read consistency among transactions, ensuring that other users will not see
your changes until your changes are committed. Neither will your changes
affect other users’ queries that started before your changes were committed.
• A high degree of scalability.
• Multiple recovery methods, including recovery to point of failure and recovery
to a specific point in time.

• High availability using several methodologies, including standby database and
replication methodologies.
Relational Theory—Briefly
In a paper presented in June 1970, “A Relational Model of Data for Large Shared Data
Banks,” Dr. E. F. Codd introduced the relational database model we still use today. Of
course, Codd and others have added to this theory. In particular, Dr. Peter Chen, pro-
fessor of computer science at Louisiana State University, originated the Entity Rela-
tionship (ER) model. He described it in a 1976 paper entitled “The Entity Relationship
Model - Toward a Unified View of Data.”
Within the relational database, data is generally stored in two-dimensional tables.
Contained within the tables are sets of rows and columns. A row represents a record
in the table, and one or more columns represent the details of that record.When dis-
cussing relational theory, the acronym ACID is used to represent the four fundamen-
tals of effective relational databases. Oracle8i provides robust support for all these
relational fundamentals.
A Atomicity. Each transaction is a separate and distinct entity. It happens in
whole or not at all.
C Consistency. Each database change is partitioned from other transactions.
Results from another transaction won’t mysteriously pop up in the middle of
another transaction. One transaction moves the database from one consistent
state to the next.
I Isolation. A transaction is not available to other users until it has been commit-
ted. If you add a department and then add an employee to that department in
the same transaction, someone else cannot see the new department added
until you have committed the transaction, which takes place after you have
added the employee record.
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D Durability. This fundamental implies that when a transaction is complete, its
presence in the database will be preserved and will not be lost. Changes, once
committed, can be recovered.
A relational database also demonstrates the principles of structures, operations,
and integrity that Codd defined. Structures are tables, indexes, and views (for example).
They are manipulated with operations. Operations are defined methods of allowing
the user access to the database and of manipulating that database. Database opera-
tions adhere to integrity rules that govern the database. Integrity rules define what
operations can be executed and when; all operations must follow these rules.
Normalization
When you’re creating a database for an online transaction processing system (OLTP),
there are generally two concerns: the speed and efficiency of transactions, and the
overall storage space required by the database. One means of achieving the best
results is normalization—the process of organizing and refining database tables to pro-
vide accurate, unambiguous results when the tables are accessed. For larger, data ware-
housing systems, the goals are generally the same, but the means to meet these goals
tend to differ.
As a database is normalized, overall storage requirements are often reduced because
there is less data redundancy. Normalization can also, however, have a negative
impact on performance (a statement that causes an argument in many camps). That
said, the benefits of normalization usually outweigh any potential loss of perfor-
mance. In fact, normalization can improve performance because, overall, less data is
processed.
Typically, we start with a normalized database. Often, however, the cost of per-
forming the joins to retrieve data is higher than the additional disk space required to
store the data in a denormalized state. Based on this and other performance factors,
we may choose to denormalize the database—tables and materialized views are cre-
ated to store data from various tables in denormalized format. Although denormaliza-
tion should not be the first line of response to query performance problems, it can
yield good results. In one case, we denormalized eight tables used in a recurring eight-

table join and got runtimes down from several hours to just seconds. Indeed, just
about any large data warehousing design comprises denormalized data stores.
Databases are typically described as being in third normal form. (You can actually
normalize your database up to sixth normal form, but this is rarely done.) Here are
the steps of normalizing an object in a database:
First Normal Remove all repeating groups.
Second Normal Link all entities to a primary key.
Third Normal Link nonkey entities by keys, supported with foreign keys.
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First Normal Form
When we normalize a database we begin with a given entity (for example, a table
called PATIENT). This entity has attributes that uniquely identify each occurrence
within the entity. Each attribute is in its own cell, and each cell has a single value.
Entities in a given column must be the same kind of information (addresses and
phone numbers cannot be mixed, for example).
When the PATIENT table is put in first normal form, all of the attributes of the
table are atomic. Thus a patient’s name will be in one column, the address in a sepa-
rate column, and the zip code in a third column; no attributes will share a given col-
umn. Another rule is that an attribute cannot contain repeating groups. Thus, in the
PATIENT table, all of the patient’s doctors cannot be listed in an attribute called DOC-
TORS (unless there is truly only one doctor per patient—not very likely!) Once all this
work has been done, the PATIENT table would be in first normal form as seen here:

PATIENT
——————————-
Patient_id
last_name
first_name
address_1
city
state
zip
doctor_name
procedure
procedure_cost
Second Normal Form
In second normal form, we remove any item that is not directly dependent on the
primary key (PK). For example, we have identified the PATIENT_ID as the primary key
of the PATIENT table. The DOCTOR_NAME columns are not dependent on the
PATIENT_ID column and thus should be removed from the PATIENT table. All these
columns are moved to their own entity (table). We end up with the following entities,
with the PATIENT table in second normal form:
PATIENT
——————————-
Patient_id - PK
last_name
first_name
address
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city

state
zip
procedure
procedure_cost
DOCTOR
——————————-
doctor_number - PK
doctor_name
DOCTOR_ASSIGNMENT
——————————-
patient_id - PK / FK
doctor_number - PK / FK
Comments
Note that the PATIENT table attributes now all relate directly to the PATIENT_ID
primary key. We have added DOCTOR table, which now contains the DOCTOR_
NAME column, since the DOCTOR_NAME column is not related to the primary key.
We also have a third table, DOCTOR_ASSIGNMENT, which relates the two tables
(PATIENT and DOCTOR) that we have just created. Also note that we created the
PATIENT_ID and DOCTOR_NUMBER columns in the DOCTOR_ASSIGNEMNT table
as primary keys, and assigned them a foreign key relationship to the related columns
in the DOCTOR and PATIENT tables. Finally, we added a COMMENTS column to the
DOCTOR_ASSIGNMENT table so the doctor assigned to the patient could record some
comment about the assignment.
Third Normal Form
In third normal form (often abbreviated to 3NF), all attributes in a given table are
dependent on every key attribute. Any nonprimary attributes that are dependent on
nonkey attributes are moved to their own table. We also ensure that no attribute is
dependent on any set of nonprimary key attributes. Then we define key relationships
between the various related tables. In our example, the PROCEDURE_COST attribute
is dependent on a nonkey attribute, PROCEDURE. We create another table called

PROCEDURE that links to the PATIENT table through a column called
PROCEDURE_ID.
Foreign key relationships, which represent a relationship between two entities, are
established in third normal form. The first entity (called the child) consists of one or
more columns that are always related to all primary key attributes of the parent.
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In this example the PROCEDURE column in the PATIENT table (the child table in
this example) violates third normal form. We need to remove the PROCEDURE column
from the PATIENT table and move it to a new table, which we will call PROCEDURE_
NAME. Still, we want to relate the two tables (PROCEDURE and PATIENT), so we cre-
ate the PROCEDURE_ID column in the PATIENT table, and relate it to the column of
the same name in the PROCEDURE table. Finally, we make the PROCEDURE_ID col-
umn in the PROCEDURE table the primary key. Now, for each patient, we can track
the procedure being performed, but there is still a problem that we need to deal with.
The PROCEDURE_ID doesn’t really belong in the PATIENT table. This is because a
given patient may need to have one or more procedures performed on them. If this
occurred, we would violate 3NF because we would end up with repeating primary
keys (multiple records for the same PATIENT_ID). Thus, we will move PROCEDURE_ID
from the PATIENT table down to the DOCTOR_ASSIGNMENT table. Finally, we will
add a PROCEDURE_DATE column in the DOCTOR_ASSIGNMENT table to make sure
that each row in that table is unique, and thus fulfilling the requirements of normal-
ization. Note in this case that the PROCEDURE_ID column in the PROCEDURE table

is not a primary key column of that table, but it does have a foreign key relationship
created between it and the PROCEDURE_ID column of the PROCEDURE table.
PATIENT

Patient_id - PK
last_name
first_name
address
city
state
zip
DOCTOR

doctor_number - PK
doctor_name
DOCTOR_ASSIGNMENT

patient_id - PK / FK
doctor_number - PK / FK
procedure_date
procedure_id - FK
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Comments
PROCEDURE

procedure_id - PK
procedure

procedure_cost
Joins
Often you will want to query two tables and produce a result from both, combined.
You show the related rows of both tables together, with each row representing the
merged rows from the two tables. This is known as a join. For example, assume you
have an employee table containing employees’ names and IDs, as well as the number
of each employee’s department. A second table, called DEPT, contains each depart-
ment number and the name assigned to that specific department (Heating and Cool-
ing, Lawn Equipment, and so on). With a join, you can query these tables to get an
employee’s name, and the name and number of the department in which they work.
An example appears in Figure 1.1.
FIGURE 1.1
An example of a join
between two tables
In the process of executing a join, the tables have various relationships to one
another. If one table of the join will always have just one record, and the other table
may have many records, this is known as a one-to-many join. If both tables of the join
will have only one record as a result of the join, this is a one-to-one join. Sometimes
both tables have many related records; this is a many-to-many join. Often these rela-
tionships are optional, or they may be required. When they are required, you end up
with a foreign key relationship.
In a foreign key relationship, columns in one table relate to the primary key
columns in another table. For instance, one or more columns in Table A (the child
table) might have a relationship to one or more primary key columns in Table B (the
parent table). The presence of parent/child relationships makes it a foreign key relation-
ship, which creates another integrity rule. Oracle enforces the foreign key relationships
Employee
EmpNo
EName
DeptNo

Parent TableChild Table
JOIN
Dept
DeptNo
DName
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via a foreign key constraint in which you define the parent/child relationship of the
tables, and Oracle then ensures that the foreign key relationship between the two
tables is enforced. Through enforcement of the foreign key relationship, logical data
consistency is enforced.
Figure 1.2 shows the one-to-one, one-to-many, and many-to-many relationships
possible in a relational design.
FIGURE 1.2
Relationships of tables
A Brief History of Oracle
Oracle was founded by Larry Ellison in 1977 as Relational Software Inc. (RSI). The first
version of RSI’s database product was called Oracle. Oracle version 2 was introduced
in 1979. It has quickly become the relational database of choice in most Fortune 500
businesses and a great number of Internet businesses. In late 1999, Oracle released its
newest version, Oracle8i. At the time of this writing, release 8.1.7 of Oracle8i was the
latest and greatest version of the Oracle database. Also, the beta for Oracle9i (release
9.0) has been announced. With Oracle8i, Oracle has introduced significant features

that indicate a long, bright future for this product. Overall performance has been
Table A Table B
One-To-One Table Relationship
A row in Table A is related to a row in Table B
Table A
Table B
One-To-Many Table Relationship
One row in Table A is related to
one or many rows in Table B
Table A
Table B
Many rows in Table A can be
related to many rows in Table B
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enhanced, and there have been improvements in Java support within the database,
data warehousing, and a number of other aspects of Oracle8i.
Oracle as a Relational Database
Oracle supports the basic constructs of relational databases. It allows for the creation
of tables and the definition of primary keys on those tables. It supports the ACID fun-
damentals as well as the principles of structures, operations, and integrity. In addi-
tion, Oracle supports multiple users and multiple transactions, all the while making
sure that you can recover your data if disaster occurs. Oracle allows you to define for-
eign keys and enforce those relationships, yet Oracle offers you the flexibility to break
those rules (or bend them a bit) when necessary.
Oracle as an Object-Oriented Database
Oracle8 introduced object-oriented functionality, which continues to evolve in Ora-
cle8i. You can create user-defined datatypes that can be used in Oracle object tables,

nested tables, VARARRAY types, and methods.
Though not yet fully object oriented, Oracle8i is a step in the right direction. As
the company continues to improve the nature of object features in Oracle, more—and
more truly object-oriented—features will be available. Chapter 6 explores the object-
oriented architecture of Oracle8i.
Oracle Internals
This section covers the basics of Oracle internals: instances and how to create them,
the SGA, Oracle processes, the physical and logical structures of an Oracle database,
and some miscellaneous but important principles such as foreign keys and NULL val-
ues. If you’re a beginning DBA, this section is critical. You need to really understand
this stuff in order to master Oracle database administration. Until the internals are
under your belt, you can go through the motions, but you won’t really understand
why you’re doing what you’re doing. So pay attention, and read on.
NOTE For the most part, this book isn’t directed toward beginners in database pro-
gramming. If you’re a beginner DBA, you will need supplemental information along your
journey through this text. You might want to look at the Sybex Study Guides for Oracle Cer-
tified Professional (OCP) certification; several of them focus on certification for the DBA.
Appendix I contains details about the Oracle Certified Professional Program.
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