Book Image

Advanced Oracle PL/SQL Developer's Guide (Second Edition) - Second Edition

By : Saurabh K. Gupta
Book Image

Advanced Oracle PL/SQL Developer's Guide (Second Edition) - Second Edition

By: Saurabh K. Gupta

Overview of this book

Oracle Database is one of the most popular databases and allows users to make efficient use of their resources and to enhance service levels while reducing the IT costs incurred. Oracle Database is sometimes compared with Microsoft SQL Server, however, Oracle Database clearly supersedes SQL server in terms of high availability and addressing planned and unplanned downtime. Oracle PL/SQL provides a rich platform for application developers to code and build scalable database applications and introduces multiple new features and enhancements to improve development experience. Advanced Oracle PL/SQL Developer's Guide, Second Edition is a handy technical reference for seasoned professionals in the database development space. This book starts with a refresher of fundamental concepts of PL/SQL, such as anonymous block, subprograms, and exceptions, and prepares you for the upcoming advanced concepts. The next chapter introduces you to the new features of Oracle Database 12c, not limited to PL/SQL. In this chapter, you will understand some of the most talked about features such as Multitenant and Database In-Memory. Moving forward, each chapter introduces advanced concepts with the help of demonstrations, and provides you with the latest update from Oracle Database 12c context. This helps you to visualize the pre- and post-applications of a feature over the database releases. By the end of this book, you will have become an expert in PL/SQL programming and will be able to implement advanced concepts of PL/SQL for efficient management of Oracle Database.
Table of Contents (19 chapters)
Advanced Oracle PL/SQL Developer's Guide Second Edition
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Oracle Database 12c enhancements to PL/SQL subprograms


Oracle Database Release 12c includes a number of PL/SQL feature enhancements. These enhancements are focused on improving the usability of PL/SQL as a language. Although the next chapter will discuss many more new features in detail, it is worthwhile to mention a few of them that are exclusively related to Oracle PL/SQL subprograms.

  • Defining PL/SQL subprograms in the SELECT statement: Although PL/SQL allows the invoking of a function from the SELECT statement, the context switch from SQL to the PL/SQL engine degraded the performance. Oracle 12c allows creating PL/SQL units in the WITH clause of a subquery and using it in the SELECT statement. The new approach to calling functions in SQL statements enhances the performance as there is no context switching across the engines. In addition, these functions are not stored in the database schema.

  • Granting roles to program units: One of the challenges in PL/SQL before Oracle 12c was that a program unit had to be created with definers rights, if it was intended to be executed by all users. A user with a lower set of privileges could perform the unauthorized changes. With Oracle 12c, granting roles to PL/SQL program units adds a levels of safety. You can now create program units with invoker's rights and control the privileges, which are required to run the program, through a role.

  • Protecting PL/SQL unit access through the ACCESSIBLE BY clause: With Oracle 12c, you can restrict access to a PL/SQL unit by unauthorized programs. A subprogram (a procedure, function or a package) can optionally include an ACCESSIBLE BY clause to define a white list of PL/SQL program units that can invoke it.