Beginning Oracle Application Express 4 - Gault_ Doug.pdf - Beginning Oracle Application Express 4 (3483) - superktos86

THE EXPERT’S VOICE ® IN ORACLE

Beginning

Oracle Application

Express 4

Your ticket to easy and robust web-application development

using Oracle's powerful toolset for power-users, programmers,

and database administrators

Doug Gault, Karen Cannell,

Patrick Cimolini, Martin Giffy D'Souza,

and Timothy St. Hilaire

For your convenience Apress has placed some of the front

matter material after the index. Please use the Bookmarks

and Contents at a Glance links to access them.

Contents at a Glance

Contents ..................................................................................................................... v

About the Authors .................................................................................................... xv

Acknowledgments .................................................................................................. xvii

Chapter 1: An Introduction to APEX 4 ..................................................................... 1

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Chapter 2: A Developer’s Overview......................................................................... 7

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Chapter 3: Identifying the Problem & Designing the Solution............................... 31

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Chapter 4: SQL Workshop...................................................................................... 39

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Chapter 5: Application and Navigation.................................................................. 61

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Chapter 6: Forms and Reports – The Basics ......................................................... 99

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Chapter 7: Forms and Reports – Advanced......................................................... 155

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Chapter 8: Programmatic Elements .................................................................... 207

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Chapter 9: Security ............................................................................................. 245

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Chapter 10: Application Deployment................................................................... 273

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Chapter 11: Understanding Websheets ............................................................... 281

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Chapter 12: A Websheet Example ....................................................................... 313

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Chapter 13: Extended Developer Tools................................................................ 333

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Chapter 14: Managing Workspaces .................................................................... 355

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Chapter 15: Team Development .......................................................................... 375

Index ....................................................................................................................... 405

C H A P T E R 1

■ ■ ■

An Introduction to APEX 4

Welcome to the wonderful world of Oracle Application Express (APEX). You’re about to learn how to use

a tool that we believe will revolutionize the way you think about and approach writing web-based Oracle

systems. It certainly has for us.

Prior to the advent of APEX, developing fully interactive web based systems over data that resided

within an Oracle database almost always meant learning a new and often complex language like Java,

.NET, or PHP and then figuring out how to integrate your chosen language seamlessly with the data that

resided in your database. Often this also meant trying to incorporate business rules that were already

coded in the form of PL/SQL.

In such situations, it could take months or even years just to become proficient enough with your

chosen language to begin to write a functional system. If you’re like many, you’ll become frustrated with

the fact that you’ve spend an inordinate amount of time to do what seems like a relatively easy task.

Fear not! The days of long-winded and complex web development platforms may just be behind us.

What is APEX?

APEX is a 100% browser-based rapid application development (RAD) tool that helps you to create rich

interactive Oracle-based web applications very quickly and with relatively little programming effort.

There are many RAD development tools and platforms on the market. If you’re dealing with data

that resides in an Oracle database, there are a number of things that makes APEX distinctive and thus

more attractive as a development platform. First and foremost is the fact that APEX is built on and uses

as its core languages, SQL, and PL/SQL. This is a huge advantage for those of you who have already been

working with the Oracle database because it means you can immediately draw on what you know. Even

for those who don’t have an Oracle background, if you are going to be working with an Oracle database,

you’ll need to learn about its particular flavor of SQL and will at some point likely find a need for the

PL/SQL procedural language.

This fact becomes even more beneficial if you are migrating an Oracle-based system to APEX that

already has a significant amount of business logic coded into stored PL/SQL program units. In this

instance, you can almost immediately take advantage of that logic with very little effort or change to the

existing code.

Another great advantage is that APEX is a declarative tool that provides a feature rich core designed

to make your job easier. Because APEX takes care of many of the underlying functions common to all

web-based applications you are able to focus on the logic specific to your application.

A large share of what you need to accomplish can be done by using one of the many built-in wizards

provided as part of the APEX Application Builder. The wizards walk you through the process of defining

what you want your application to do and then stores that information as metadata. Once the wizard is

complete you can edit and enhance the functionality, or even replace it with your own custom SQL and

PL/SQL routines. After you become proficient with APEX you might even find yourself bypassing the

wizards altogether and generating more complex definitions directly.

CHAPTER 1 ■ AN INTRODUCTION TO APEX 4

During the course of the book, you will discover that you will likely want a few other tools at your

disposal, but in truth, you could easily develop a very rich application using nothing but your web

browser and what APEX provides for you.

A Brief History of APEX

APEX has been around for quite some time—perhaps even longer than most people know. The first

public release of APEX, or HTML DB as it was called then, came in 2004, but its history reaches back

quite a long way.

Ancient History

APEX has its roots in technology that has been around for quite some time. In fact, parts of the PL/SQL

Web Toolkit, which is used under the covers by APEX to generate the HTML that is sent to the browser,

date back to as early as 1994.

At that point in time, you could actually write web applications in PL/SQL by hand, and

unfortunately we did. This required not only a thorough knowledge of PL/SQL and HTML but also the

patience of a saint and the determination of a headstrong mule. The end result wasn’t very pretty, and it

was definitely not secure by today’s terms, but it was functional, if somewhat limited.

Not long after, Oracle introduced PL/SQL Server Pages (PSPs). This involved first coding the static

HTML and including special Oracle markup to indicate where dynamic data would go. Once you had the

output looking as you wanted, you then ran it through a program called

LOADPSP

. This would translate

the raw HTML and the special Oracle markup into a PL/SQL procedure that, again, used the PL/SQL

Web Toolkit to emit the HTML including the dynamic data you requested. At the time, this was a huge

leap forward. I worked at a company where we actually built an entire framework around using PSP

technology and deployed it at several clients.

Finally, in 1997, WebDB came on the scene. The true grandfather of what we now call APEX, WebDB

was revolutionary in that it was a 100% web-based tool that allowed developers to design web

applications. It was written entirely in PL/SQL even though Java seemed to be taking over the world.

Developers could point WebDB at their database and generate code that would produce forms, reports,

charts, and calendars. There was no session state management or templates; once the code was

generated, there was no going back through the tool.

WebDB allowed a large number of companies who wanted to jump on the web-based bandwagon to

do so without spending vast amounts of time and effort in retraining their staff. As a tribute to its

success, I know of a number of companies that still have WebDB system running in production

environment.

Unfortunately WebDB’s days were numbered. Because it generated code (and if you didn’t like the

code it generated, then too bad for you), it had already begun to fade from favor by the time it was

absorbed into Oracle’s Portal product. However, creator Mike Hichwa did not forget the glimpse of

greatness that WebDB had seen.

More Recent History

Around 1999, Oracle’s CEO, Larry Ellison presented Mike Hichwa (VP of Software Development) with the

task of creating an internal calendaring and scheduling system for Oracle Corp. The original remit was to

use WebDB to generate the initial code and then hand code all the changes from that point forward.

Mike, however, saw this as an opportunity to completely re-write WebDB into something that could be

far more useful. Thus, with the help of Joel Kallman and Tom Kyte, Oracle Flows was born.

Based on the success of the internal Calendaring and Scheduling system, the team was allowed to

move forward towards making Oracle Flows a product. In 2001, using what then known as Flow Builder,

Beginning Oracle Application Express 4 - Gault_ Doug.pdf

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