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

Table of Contents

Advanced Oracle PL/SQL Developer's Guide Second Edition

Credits

About the Author

About the Reviewers

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Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Downloading the example code

Errata

Piracy

Questions

1. Overview of PL/SQL Programming Concepts

Introduction to PL/SQL

PL/SQL program fundamentals

Cursors – an overview

The cursor execution cycle

Cursor attributes

Cursor FOR loop

Exception handling in PL/SQL

System-defined exceptions

User-defined exceptions

The RAISE_APPLICATION_ERROR procedure

Exception propagation

Creating stored procedures

Executing a procedure

Functions

Functions – execution methods

Restrictions on calling functions from SQL expressions

A PL/SQL package

Oracle Database 12c enhancements to PL/SQL subprograms

Managing database dependencies

Displaying the direct and indirect dependencies

Dependency metadata

Dependency issues and enhancements

Reviewing Oracle-supplied packages

Oracle SQL Developer

Oracle SQL Developer for DBA, Developers, and Application Architects

SQL Developer 4.0

Summary

Practice exercise

2. Oracle 12c SQL and PL/SQL New Features

Database consolidation and the new Multitenant architecture

The Oracle Database 12c Multitenant architecture – features

Multitenant for Consolidation

Plug/unplug

Manage Many as One

Rapid provisioning

CDB Resource Management

Common users and local users

Oracle 12c SQL and PL/SQL new features

IDENTITY columns

Default column value to a sequence in Oracle 12c

The DEFAULT ON NULL clause

Support for 32K VARCHAR2

Row limiting using FETCH FIRST

Invisible columns

Temporal databases

In-Database Archiving

Defining a PL/SQL subprogram in the SELECT query and PRAGMA UDF

Test setup

Comparative analysis

The PL/SQL program unit white listing

Granting roles to PL/SQL program units

Test setup

Miscellaneous PL/SQL enhancements

The Oracle Database 12c (12.1.0.2) In-Memory option

The challenge

The problem statement and Oracle Database 12c In-Memory

Oracle Database 12c In-Memory option features

The Oracle Database 12c In-Memory Architecture

Controlling the In-Memory column store

The INMEMORY clause

Performance optimizations

In-Memory Advisor

Oracle Database In-Memory benefits

Summary

3. Designing PL/SQL Code

Cursor structures

Cursor execution cycle

Cursor attributes

Implicit cursors

Explicit cursors

Cursor variables

Strong and weak ref cursor types

Working with cursor variables

SYS_REFCURSOR

Cursor variables as arguments

Cursor variables – restrictions

Cursor design considerations

Cursor design–guidelines

Implicit statement results in Oracle Database 12c

Subtypes

Subtype classification

Type compatibility with subtypes

Summary

Practice exercise

4. Using Collections

Introduction to collections

Collection types

Associative arrays

Nested tables

Modify and drop a nested table object type

Design considerations of a nested table

Nested table storage

Nested table in an index - organized table

Nested table locators

Nested table as the schema object

Operations on a nested table type column

Create a nested table instance

Querying a nested table column

Nested table collection type in PL/SQL

Collection initialization

Querying the nested table metadata

Nested table comparison functions

Multiset operations on nested tables

Varray

Varray as a schema object

Operations on varray type columns

Inserting varray collection type instance

Querying varray column

Updating the varray instance

Varray in PL/SQL

Comparing the collection types

Selecting the appropriate collection type

Oracle 12c enhancements to collections

PL/SQL collection methods

EXISTS

COUNT

LIMIT

FIRST and LAST

PRIOR and NEXT

EXTEND

TRIM

DELETE

Summary

Practice exercise

5. Using Advanced Interface Methods

Overview of External Procedures

External Procedures

Components of external procedure execution flow

The extproc agent

The Library object

Callout and Callback

Call Specification

How an External Procedure executes

Environment setup

TNSNAMES.ora

EXTPROC.ora

Executing external C programs from PL/SQL

Securing External Procedures with Oracle Database 12c

Executing Java programs from PL/SQL

Loading a Java class into a database

Steps to execute a Java class from an Oracle PL/SQL unit

Summary

Practice exercise

6. Virtual Private Database

Oracle Database Security overview

Fine-Grained Access Control

How FGAC works

Virtual Private Database

How does Virtual Private Database work?

Column-level Virtual Private Database

Virtual Private Database with Oracle Database 12c Multitenant

Virtual Private Database components

Application Context

Virtual Private Database policy function

Policy types

The DBMS_RLS package

Demonstration

Virtual Private Database features and best practices

Virtual Private Database metadata

Policy utilities—refresh and drop

Oracle Database 12c Security enhancements

Oracle Database 12c Data Redaction

Data Redaction exemptions and miscellaneous features

Data Redaction function types

Demonstration

The Data Redaction metadata

Summary

Practice exercise

7. Oracle SecureFiles

Introduction to Large Objects

Classification of Large Object datatypes

Internal LOB

Persistent and Temporary LOB

External LOB

LOB restrictions

LOB data types in Oracle

BLOB and CLOB

BFILE

Some more related stuff

The LOB locator

LOB instance initialization

The DBMS_LOB package

The DBMS_LOB constants

The DBMS_LOB data types

The DBMS_LOB subprograms

LOB usage notes

Oracle SecureFiles

Deduplication and compression

Encryption

File System Logging

Write Gather Cache

Free space management

BasicFiles and SecureFiles

The db_securefile parameter

Working with LOBs

LOB metadata

Enabling the advanced features of a SecureFile

Populating the LOB data

Temporary LOB operations

Managing temporary LOBs

Working with a temporary LOB

Migrating LONG to LOBs

Use the ALTER TABLE command

Using the TO_LOB function

Online Table Redefinition

Migrating BasicFiles to SecureFiles

Oracle Database 12c enhancements to SecureFiles

Summary

Practice exercise

8. Tuning the PL/SQL Code

The PL/SQL Compiler

Subprogram inlining in PL/SQL

PRAGMA INLINE

PLSQL_OPTIMIZE_LEVEL

Case 1: When PLSQL_OPTIMIZE_LEVEL = 0

Case 2: When PLSQL_OPTIMIZE_LEVEL = 1

Case 3: When PLSQL_OPTIMIZE_LEVEL = 2

Case 4: When PLSQL_OPTIMIZE_LEVEL = 3

Native and interpreted compilation techniques

Oracle Database 11g Real Native Compilation

Selecting the appropriate compilation mode

Setting the compilation mode

Querying the compilation settings

Compiling a program unit for native or interpreted compilation

Recompiling a database for a PL/SQL native or interpreted compilation

Tuning PL/SQL code

Build secure applications using bind variables

Call parameters by reference

Avoiding an implicit data type conversion

Understanding the NOT NULL constraint

Selection of an appropriate numeric data type

Bulk processing in PL/SQL

BULK COLLECT

FORALL

FORALL and exception handling

Summary

Practice exercise

9. Result Cache

Oracle Database 11g Result Cache

What is the Server Result Cache?

Configuring the Server Result Cache

Result Cache versus Buffer Cache

Result Cache versus Oracle 12c Database In-Memory

Result Cache versus In-Memory Database Cache

SQL query Result Cache

Monitoring the SQL Result Cache

Invalidation of the SQL Result Cache

Read consistency of the SQL Result Cache

Limitations

PL/SQL Function Result Cache

Does it sound similar to deterministic functions?

Differences between Result Cache and other caching techniques

Illustration

Monitoring the PL/SQL Result Cache

Invalidation of the PL/SQL Result Cache

Limitation

OCI Client results cache

The DBMS_RESULT_CACHE package

Displaying the result cache memory report

Oracle Database 12c enhancements to the PL/SQL function Result Cache

Result cache in Real Application Clusters

Summary

Practice exercise

10. Analyzing, Profiling, and Tracing PL/SQL Code

A sample PL/SQL program

Tracking PL/SQL coding information

USER_ARGUMENTS

USER_OBJECTS

USER_OBJECT_SIZE

USER_SOURCE

USER_PROCEDURES

USER_PLSQL_OBJECT_SETTINGS and USER_STORED_SETTINGS

USER_DEPENDENCIES

The DBMS_DESCRIBE package

Tracking the program execution subprogram call stack

Tracking propagating exceptions in PL/SQL code

Determining identifier types and usages

USER_IDENTIFIERS

The PL/Scope tool

The PLSCOPE_SETTINGS parameter

The DBMS_METADATA package

DBMS_METADATA data types and subprograms

Parameter requirements

The DBMS_METADATA transformation parameters and filters

Demonstration

Tracing PL/SQL programs using DBMS_TRACE

Installing the DBMS_TRACE package

DBMS_TRACE subprograms

Compiling a PL/SQL program for debugging

Viewing the PL/SQL trace information

Steps to trace PL/SQL program execution

Profiling PL/SQL code

The DBMS_HPROF package

Differences between DBMS_PROFILER and DBMS_HPROF

DBMS_HPROF subprograms

Collecting raw profile data

Interpreting the raw profiler data

Analyzing profiler data

Creating the profiler tables

Analyzing the profiler output

Querying the profiler tables

The plshprof utility

What do these reports reveal?

Summary

Practice exercise

11. Safeguarding PL/SQL Code against SQL injection

What is SQL injection?

SQL injection targets

How to exploit the PL/SQL code?

Preventing SQL injection attacks

Sanitizing inputs using DBMS_ASSERT

Choose the right subprogram for the right identifier

Unquoted identifiers

Quoted identifiers

Literals

DBMS_ASSERT – limitations

Use of bind variables to prevent injection attacks

Best practices to avoid SQL injection

Testing the code for SQL injection flaws

Test strategy

An effective code review

Static code analysis

Fuzz tools

Generating test cases

Summary

Practice exercise

12. Working with Oracle SQL Developer

An overview of SQL Developer

Key differentiators

History and background

SQL Developer for Developers

SQL Developer for Database Administrators

SQLcl – The new SQL command line

Getting started with SQL Developer

Creating a database connection

Using the SQL worksheet

Core features of SQL Developer

Object Browser

PL/SQL Editor and Debugger

DBA Panel

Database Utilities

The Data Modeler

SQL Developer reports

Version control

The SQL Translation Framework

SQL Developer 4.0 and 4.1 New Features

Summary

Index

Advanced Oracle PL/SQL Developer's Guide Second Edition

Advanced Oracle PL/SQL Developer's Guide Second Edition

Copyright © 2016 Packt Publishing

All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, without the prior written permission of the publisher, except in the case of brief quotations embedded in critical articles or reviews.

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First published: May 2012

Second edition: February 2016

Production reference: 1080216

Published by Packt Publishing Ltd.

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ISBN 978-1-78528-480-9

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Credits

Author

Saurabh K. Gupta

Reviewers

Kamran Aghayev A

Patrick Barel

Nassyam Basha

Ramakrishna Kandula

Wissem EL Khlifi

Sean Stacey

Davor Zelic

Commissioning Editor

Priya Singh

Acquisition Editor

Tushar Gupta

Content Development Editor

Arwa Manasawala

Technical Editor

Rohan Uttam Gosavi

Copy Editor

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Project Coordinator

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Proofreader

Safis Editing

Indexer

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Graphics

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Production Coordinator

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Cover Work

Nilesh R. Mohite

About the Author

Saurabh K. Gupta is a seasoned database technologist with extensive experience in designing high performance and highly available database applications. His technology focus has been centered around Oracle Database architecture, Oracle Cloud platform, Database In-Memory, Database Consolidation, Multitenant, Exadata, Big Data, and Hadoop. He has authored the first edition of this book. He is an active speaker at technical conferences from Oracle Technology Network, IOUG Collaborate'15, AIOUG Sangam, and Tech Days. Connect with him on his twitter handle (or SAURABHKG) or through his technical blog www.sbhoracle.wordpress.com, with comments, suggestions, and feedback regarding this book.

About the Reviewers

Patrick Barel is a PL/SQL developer for AMIS Services (http://www.amis.nl/) in the Netherlands. Besides working with SQL and PL/SQL, he co-developed CodeGen together with Steven Feuerstein, and has written different plugins (http://bar-solutions.com/) for PL/SQL developer at (http://www.allroundautomations.com/). He publishes articles on AMIS Technology Blog (http://technology.amis.nl/blog) and on his own blog (http://blog.bar-solutions.com).

He has been a reviewer for several books including Oracle PL/SQL Programming by Steven Feuerstein. He has been an Oracle ACE since 2011.

Nassyam Basha is a database administrator and an Oracle ACE Director. He holds a master's degree in Computer Applications from the University of Madras. He is an Oracle 11g Certified Master and Exadata implementation specialist, and has good knowledge of Oracle technologies, such as Data Guard, RMAN, RAC, and Exadata. He actively participates in Oracle-related forums, such as OTN, where he has superhero status. He maintains an Oracle-technology-related blog (www.oracle-ckpt.com) and has coauthored Oracle Data Guard 11gR2 administration beginners guide, Packt Publishing. He actively writes many articles on OTN in various languages. He is a speaker at OTN, IOUG, and SANGAM, and he is the co-founder of Oraworld-team (www.oraworld-team.com). He is part of the AIOUG community on Twitter, where he occasionally expresses his views via the Twitter handle @AIOUG. He is currently working with Pythian as an Oracle database consultant.

Nassyam Basha has written Oracle Data Guard 11gR2 Beginner's Guide, Packt Publishing.

I want to thank the almighty Allah and my parents, Abdul Aleem and Rahimunnisa, for their support and blessings all the time—without them, nothing is possible. Special thanks to my wife and 9-month-old daughter Yashfeen Fathima, who've shared a lot of fun and crazy things with me while I worked on this book, and, as always, I would also like to thank my brother, Nawaz, and my cousins, for their great support. Finally, thanks to Saurabh Gupta for referring me as a technical reviewer, which was not an easy task for me, as this is my first assignment as a reviewer. He did a great job on this book.

Wissem El Khlifi is the first Oracle ACE in Spain and an Oracle Certified Professional DBA with over 12 years of IT experience.

He earned his Computer Science engineering degree from FST Tunisia, his master's degree in Computer Science from the UPC, Barcelona, and another master's degree in Big Data Science from the UPC, Barcelona.

His areas of interest are Linux System Administration, Oracle ERP and Databases (RAC and Dataguard), big data NoSQL database management, and big data analysis.

His career has included the roles of Oracle and Java analyst/programmer, Oracle DBA, architect, team leader, and big data scientist. He currently works as senior database and application engineer for Schneider Electric/APC.

He writes numerous articles on his website, http://www.oracle-class.com, and you can contact him via Twitter at @orawiss.

Davor Zelic is an IT professional with more than 15 years of experience in designing, developing, and implementing IT systems.

After getting his master's degree in Electrical Engineering, he began his professional career working with Oracle technology in the Croatian IT company TEB Informatika. For more than 10 years, Davor worked on IT projects related to road management, where he gained extensive experience working as an Oracle SQL, PLSQL, Forms, and Reports and Spatial developer. He has proved his knowledge by becoming an Oracle Certified Professional issued by the Oracle Corporation.

Apart from Oracle technology, Davor has gained expertise in design and development of geographic information systems for collection, storage, transformation, analysis, and visualization of geo-referenced data. He originally worked with Intergraph technology, but later his focus moved to open source GIS technologies, such as Geoserver and OpenLayers.

Davor currently works as a software architect at the IT department of Croatian Central Bank, designing software solutions for Croatian financial market data collection and analysis.

I want to thank my parents for the support that they gave me in choosing my educational path, which allowed me to find a job that is not just a routine, but also a source of satisfaction and constant challenge.

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Preface

How many of us would believe that PL/SQL was introduced as a scripting language for executing a bunch of SQL scripts? Well, that's true. With the growing need to build computational logic and condition-based constructs, and to manage exception rules within databases, Oracle Corporation first released PL/SQL along with Oracle Database Version 6.0 with a limited set of capabilities. Within its capacity, PL/SQL was capable of creating program units that could not be stored inside the database. Eventually, Oracle's release in the application line, SQL *Forms version V3.0, included the PL/SQL engine and allowed developers to implement the application logic through procedures. Back then, PL/SQL used to be part of the transaction processing option in Oracle 6 and the procedural option in Oracle 7. Since the time of its ingenuous beginning, PL/SQL has matured immensely as a standard feature of Oracle Database. It has been enthusiastically received by the developer community, and the credit goes to its support for advanced elements such as modular programming, encapsulation, support for objects and collections, program overloading, native and dynamic SQL, and exception handling.

PL/SQL is loosely derived from Ada (named after Ada Lovelace, an English mathematician who is regarded as the first computer programmer), a high-level programming language, which complies with the advanced programming elements. Building a database backend for an application demands the ability to design the database architecture, skills to code complex business logics, and expertise in administering and protecting the database environment. One of the principal reasons why PL/SQL is a key enabler in the development phase is its tight integration with Oracle's SQL language. In addition to this, it provides a rich platform for implementing the business logic in the Oracle Database layer and store them as procedures or functions for subsequent use. As a procedural language, PL/SQL provides a diverse range of datatypes, iterative and control constructs, conditional statements, and exception handlers.

In a standard software development space, an Oracle database developer is expected to get involved in schema design; code business logics on the server side by using functions, procedures, or packages; implement action rules by using triggers; and support client-side programs in setting up the application interface. While building the server-side code, developers should understand that their code contributes to the application's performance and scalability. Language basics are expected to be resilient, but while building robust and secure applications using PL/SQL, developers must take advantage of best practices and try to use advanced language features. This book focuses on the advanced features of PL/SQL validated up to the latest Oracle Database 12c.

Learning by example has always been a well-attested approach for diving deep into a concept. This book will enable you to master the latest enhancements and new features of Oracle Database 12c. For efficient reading, you just have to be familiar with the PL/SQL fundamentals so that you can relate to the evolution of an advanced feature from its ever-expanding roots.

This book closely follows the outline of the Oracle University certification; that is, the Oracle Certified Advanced PL/SQL Developer Professional (1Z0-146) exam. One of the most sought after certifications in the developer community, the 1Z0-146 certification's objectives are quite comprehensive, and touch upon the various progressive areas of PL/SQL. To name a few, PL/SQL code performance, maintenance, bulk processing techniques, PL/SQL collections, security implementation, and the handling of large objects. For certification aspirants, this book will serve as a one-stop exam guide. At many stages, this book goes beyond the certification objectives and attempts to build a deep understanding of the concepts. Therefore, mid-level database developers will find this book a handy language reference and would be keen to have it on their bookshelves.

My last work on the same subject will remain close to my heart, but this one is straight from my experience. I hope that this book will help you improve your PL/SQL development skills and gain confidence in using advanced features, along with meticulous familiarization of Oracle Database 12c.

What this book covers

Chapter 1, Overview of PL/SQL Programming Concepts, provides an overview of PL/SQL fundamentals. It refreshes the basic concepts, such as PL/SQL language features, the anonymous block structure, exception handling, and stored subprograms.

Chapter 2, Oracle 12c SQL and PL/SQL New Features, talks about the new features of Oracle Database 12c. It starts with the idea of consolidation of databases on a cloud and how the Oracle 12c Multitenant architecture addresses the requirements. It consolidates the new features in Oracle 12c SQL and PL/SQL, and explains each of them with examples. It will help you to feel the essence of Oracle Database 12c and understand what the driving wheel of innovation is. A section on the Oracle Database 12c In-memory option will familiarize you with the breakthrough feature in the analytics and warehouse space.

Chapter 3, Designing PL/SQL Code, primarily focuses on the PL/SQL cursor's design and handling. You will get to learn the basics of cursor design, cursor types and cursor variables, handling cursors in PL/SQL, and design guidelines. This chapter will also include the enhancements made by Oracle Database 12c with respect to cursors.

Chapter 4, Using Collections, introduces you to the world of collections; namely, associative arrays, nested tables, and varrays. Taking you all the way from their creation in SQL and PL/SQL to design considerations, this chapter makes you wise enough to choose the right collection type in a given situation. A section on Oracle Database 12c enhancements to collections introduces a very handy feature that will allow you to join a table and collection.

Chapter 5, Using Advanced Interface Methods, focuses on a powerful feature of PL/SQL: how to execute external procedures in PL/SQL. You will learn and understand the specifics of executing a C or Java program in PL/SQL as an external procedure through step-by-step demonstration. This chapter also mentions the Oracle Database 12c enhancement which allows you to secure external procedures through an additional safety net.

Chapter 6, Virtual Private Database, provides a detailed overview of the Oracle Database Security Defense-in-depth architecture and focuses on one of the developer-centric features, known as the Virtual Private Database. Oracle Database 12c security enhancements and a demonstration of data redaction will make you understand Oracle's security offerings.

Chapter 7, Oracle SecureFiles, provides a thorough understanding of handling large objects in Oracle and focuses on storage optimizations made by SecureFiles. Introduced in Oracle 11g, SecureFiles is the new storage mechanism that scores high on its advanced features, such as compression, encryption, and deduplication. This chapter also helps you with the recommended migration methods from older LOBs to SecureFiles.

Chapter 8, Tuning the PL/SQL Code, introduces the best practices for tuning PL/SQL code. It starts with the PL/SQL optimizer and rolls through the benefits of native compilation, PL/SQL code writing skills, and code evaluation design. This chapter includes the changes in Oracle 12c with respect to large object handling.

Chapter 9, Result Cache, explains the result caching feature in Oracle Database. It is a powerful caching mechanism that enhances the performance of SQL queries and PL/SQL functions that are repeatedly executed on the server. This chapter also discusses the enhancements made to the feature in Oracle Database 12c.

Chapter 10, Analyzing, Profiling, and Tracing PL/SQL Code, details the techniques used to analyze, profile, and trace PL/SQL code. If you are troubleshooting PL/SQL code for performance, you must learn the profiling and tracing techniques. In an enterprise application environment, these practices are vital weapons in a developer's arsenal.

Chapter 11, Safeguarding PL/SQL Code against SQL injection, describes ways to protect your PL/SQL from being attacked. A vulnerable piece of code is prone to malicious attacks and runs the risk of giving away sensitive information. Efficient code writing and proofing the code from external attacks can help to minimizing the attack surface area. In this chapter, you will learn the practices for safeguarding your code against external threats.

Chapter 12, Working with Oracle SQL Developer, describes the benefits of the Oracle SQL Developer for developers, database administrators, and architects. This chapter not only helps you get started with SQL Developer, but also helps you gain a better understanding of the new features of SQL Developer 4.0 and 4.1.

What you need for this book

If you are good with PL/SQL development basics, I'm sure you will enjoy reading this book. You will learn new ways to program efficiently in PL/SQL.

Who this book is for

This book is for Oracle developers who are responsible for database management. Readers are expected to have basic knowledge of the Oracle Database and the fundamentals of PL/SQL programming. Certification aspirants can use this book to prepare for the 1Z0-146 examination in order to be come an Oracle Certified Professional in Advanced PL/SQL.

Conventions

In this book, you will find a number of styles of text that distinguish between different kinds of information. Here are some examples of these styles, and an explanation of their meaning.

Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: The modified SELECT query is then executed in the HR schema of the database.

A block of code is set as follows:

/*Create the stored procedure to set the context attribute*/

CREATE OR REPLACE PROCEDURE p_app_context (p_val VARCHAR2)

IS

BEGIN

  /*Create a namespace DEMO_CONTEXT*/

  DBMS_SESSION.SET_CONTEXT(

    NAMESPACE => 'DEMO_CONTEXT',

    ATTRIBUTE => 'COUNTRY',

    VALUE    =>  P_VAL);

  END;

/

New terms and important words are shown in bold. Words that you see on the screen, in menus or dialog boxes for example, appear in the text like this: This is how interpreted compilation works. In the case of native compilation,, a sharable dynamic linked library (DLL) is generated instead of a machine code.

Note

Warnings or important notes appear in a box like this.

Tip

Tips and tricks appear like this.

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