Book Image

OCA Oracle Database 11g: SQL Fundamentals I: A Real World Certification Guide ( 1ZO-051 )

By : Steve Ries
Book Image

OCA Oracle Database 11g: SQL Fundamentals I: A Real World Certification Guide ( 1ZO-051 )

By: Steve Ries

Overview of this book

<p>The Oracle Database 11g: SQL Fundamentals I exam is the first stepping stone in getting the Oracle Certified Associate Certification for Oracle Database 11g. The SQL programming language is used in every major relational database today and understanding the real world application of it is the key to becoming a successful DBA.<br /><br />This book gives you: the essential real world skills to master relational data manipulation with Oracle SQL and prepares you to become an Oracle Certified Associate. Beginners are introduced to concepts in a logical manner while practitioners can use it as a reference to jump to relevant concepts directly.<br /><br />We begin with the essentials of why databases are important in today's information technology world and how they work.<br /><br />We continue by explaining the concepts of querying and modifying data in Oracle using a range of techniques, including data projection, selection, creation, joins, sub-queries and functions. Finally, we learn to create and manipulate database objects and to use them in the same way as today's expert SQL programmers.<br /><br />This book prepares you to master the fundamentals of the SQL programming language using an example-driven method that is easy to understand<br /><br />This definitive certification guide provides a disciplined approach to be adopted for successfully clearing the 1Z0-051 SQL Fundamentals I exam, which is the first stepping stone towards attaining the OCA on Oracle Database 11g certification.<br /><br />Each chapter contains ample practice questions at the end. A full-blown mock test is included for practice so you can test your knowledge and get a feel for the actual exam.</p>
Table of Contents (20 chapters)
OCA Oracle Database 11g: SQL Fundamentals I: A Real-World Certification Guide
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Understanding the principles of joining tables


So far, we have seen several ways to select data from tables. In Chapter 2, SQL SELECT Statements, and Chapter 3, Using Conditional Statements, we covered numerous ways to retrieve data and then limit its retrieval by condition. In Chapter 1, SQL and Relational Databases, we extensively discussed the concept of relational databases. In that chapter, we stated that what makes a relational database different from a flat file database are the relationships between entities, or in our case, tables. Up to now, we haven't seen the effect of these inter-table relationships. Each of our queries is applied only to one table. So, while each of these queries have been effective for our needs, those needs have never gone beyond the search for data from a single table. In short, if called on to do so, how would we pull data from multiple tables with a single query?

Accessing data from multiple tables

Consider the columns from two tables, shown in the following...