Of course, there was an awful lot youcouldn’tdo with PL /SQL 1.0—such as build complex,
robust, large-scale applications, or read and write operating system files, or manipulate data in
array structures, or debug your code effectively, or store your business formulas in reusable
program units.
Sure, life was simpler back when you were stuck with PL /SQL 1.0. You just too frequently told
your manager or your users that what they wanted done was, well, impossible. Fortunately, Oracle
recognized that it would be so much nicer for both its users and its bottom line if its bedrock
technology (most importantly, the Oracle RDBMS and PL /SQL) could actually meet user needs.
So it came out with PL /SQL Version 2 (which works with Version 7 of the Oracle Server) and
then, most recently, PL /SQL Version 8.0 (to accompany Oracle8). In each major version and its
sub-releases (2.1, 2.2, 2.3, and, sometime in 1998, 8.1), Oracle has added major new functionality.
As a result, hundreds of thousands of software programmers now use PL /SQL to implement
sophisticated applications.
Easily the most important new feature of PL /SQL2 was the introduction of packages. Packages
(explored in more detail in the next section) allow you to collect together related program
elements and control access to those elements. Anyone who develops PL /SQL applications
should employ packages at the very core of their layers of reusable code—and Oracle Corporation
itself is no exception. Starting with PL /SQL 2.0 and continuing through every subsequent release,
Oracle has made available to PL /SQL developers a series ofbuilt-in packages, which extend the
functionality of PL /SQL in many fascinating and important directions.
It is no longer sufficient to be aware of and expert in only the core elements of PL /SQL. Getting a
handle on IF statements, loops, and the built-in functions like INSTR and TO_CHAR is now only
the first phase in your journey towards PL /SQL expertise. To take full advantage of the PL /SQL
language, developers must now also learn how to use the programs contained in the built-in
packages. And, believe me, once you make a few discoveries in these built-in packages, you will
be amazed— and you will be addicted. You will eagerly troll this book for features you can apply
in new and creative ways to solve your problems.
This first chapter introduces you to basic concepts of package usage in PL /SQL, shows you how
to use built-in packaged functionality in your programs, and explains how to find and learn from
the source code for these packages.
( ! '
Most of the built-in packages extend the PL /SQL language to support features that would
otherwise be unavailable to you. This is possible because when Oracle Corporation builds a
package, they have the luxury of writing elements of the package in C, giving them full access to
the underlying operating system and other areas of technology that are off-limits to the rest of us
poor PL /SQL programmers. The result is that Oracle is making something available to us which
we could not get ourselves, no matter how proficient a PL /SQL programmer we become.
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