Oracle Essentials [Electronic resources] : Oracle Database 10g, 3rd Edition نسخه متنی

1.4 Database Application Development Features

The main use of the
Oracle database system is to store and retrieve data for
applications. The features of the Oracle database and related
products described in this section are used to create applications.
We''ve divided the discussion in this section into
two categories: database programming and database extensibility
options. Later in this chapter, we describe the Oracle Developer
Suite, a set of optional tools used in Oracle Database Server and
Oracle Application Server development.

1.4.1 Database Programming

All flavors of the Oracle database
include different languages and interfaces that allow programmers to
access and manipulate the data in the database. Database programming
features usually interest two groups: developers building
Oracle-based applications that will be sold commercially, and IT
organizations within companies that custom-develop applications
unique to their businesses. The following sections describe the
languages and interfaces supported by Oracle.

1.4.1.1 SQL

The ANSI standard Structured Query Language (SQL)
provides basic functions for data manipulation, transaction control,
and record retrieval from the database. However, most end users
interact with Oracle through applications that provide an interface
that hides the underlying SQL and its complexity.

1.4.1.2 PL/SQL

Oracle''s
PL/SQL, a procedural
language extension to SQL, is commonly used to implement program
logic modules for applications. PL/SQL can be used to build stored
procedures and triggers, looping controls, conditional statements,
and error handling. You can compile and store PL/SQL procedures in
the database. You can also execute PL/SQL blocks via
SQL*Plus, an interactive tool provided with
all versions of Oracle. Oracle Database 10g includes a more optimized
version of the core PL/SQL engine, as Oracle9i
allowed creation and storage of precompiled PL/SQL program units.

1.4.1.3 Java features and options

Oracle8i introduced
the use of Java as a procedural language with a
Java Virtual Machine (JVM) in the
database (originally called JServer). JVM includes support for Java
stored procedures, methods, triggers, Enterprise
JavaBeans™ (EJBs), CORBA, and HTTP. The Accelerator
is used for project generation, translation, and compilation, and can
also be used to deploy/install shared libraries.

The inclusion of Java within the Oracle database allows Java
developers to leverage their skills as Oracle application developers.
Java applications can be deployed in the client,
Application Server, or database, depending
on what is most appropriate. We discuss Java development in
Chapter 13 and Chapter 14.

Oracle data warehousing options for OLAP and data mining provide a
Java API. These applications are typically custom built using
Oracle''s JDeveloper.

1.4.1.4 Large objects

Interest in the use of large objects (LOBs) continues to grow,
particularly for storing nontraditional datatypes such as images. The
Oracle database has been able to store large objects for some time.
Oracle8 added the capability to store multiple LOB columns in each
table. Oracle Database 10g essentially removes the space limitation
on large objects.

1.4.1.5 Object-oriented programming

Support of object structures has been included since
Oracle8i to allow an
object-oriented approach to programming.
For example, programmers can create user-defined datatypes, complete
with their own methods and attributes. Oracle''s
object support includes a feature called Object Views through which
object-oriented programs can make use of relational data already
stored in the database. You can also store objects in the database as
varying arrays (VARRAYs), nested tables, or index organized tables
(IOTs). We discuss the object-oriented features of Oracle further in
Chapter 13.

1.4.1.6 Third-generation languages (3GLs)

Programmers can
interact with the Oracle database from C, C++,
Java,
COBOL, or
FORTRAN applications
by embedding SQL in those applications. Prior to compiling the
applications using a platform''s native compilers,
you must run the embedded SQL code through a precompiler. The
precompiler replaces SQL statements with library calls the native
compiler can accept. Oracle provides support for this capability
through optional "programmer"
precompilers for languages such as C and C++ (Pro*C) and COBOL
(Pro*COBOL). More recently, Oracle added
SQLJ, a precompiler for
Java that replaces SQL statements embedded in Java with calls to a
SQLJ runtime library, also written in Java.

1.4.1.7 Database drivers

All versions of Oracle include database drivers that allow
applications to access Oracle via ODBC (the Open DataBase Connectivity
standard) or JDBC (the Java DataBase
Connectivity open standard). Also available are data providers for
OLE DB and for .NET.

1.4.1.8 The Oracle Call Interface

If you''re an experienced programmer seeking optimum
performance, you may choose to define SQL statements within
host-language character strings and then explicitly parse the
statements, bind variables for them, and execute them using the

Oracle Call Interface (OCI).

OCI is a much more detailed interface that requires more programmer
time and effort to create and debug. Developing an application that
uses OCI can be time-consuming, but the added functionality and
incremental performance gains often make spending the extra time
worthwhile.

1.4.1.9 National Language Support

National Language Support (NLS)
provides character sets and associated functionality, such as date
and numeric formats, for a variety of languages.
Oracle9i featured
full Unicode 3.0 support. All data may be stored as Unicode, or
select columns may be incrementally stored as
Unicode. UTF-8
encoding and UTF-16 encoding provide support for more than 57
languages and 200 character sets. Oracle
Database 10g adds support for Unicode 3.2. Extensive localization is
provided (for example, for data formats) and customized localization
can be added through the Oracle Locale Builder. Oracle Database
10g includes a Globalization Toolkit for creating
applications that will be used in multiple languages.

1.4.1.10 Availability

All of these database programming features are included in both
Oracle Standard Edition and Oracle Enterprise Edition.

1.4.2 Database Extensibility

The
Internet and corporate intranets have created a growing demand for
storage and manipulation of nontraditional datatypes within the
database. There is a need for extensions to the standard
functionality of a database for storing and manipulating image,
audio, video, spatial, and time series information. These
capabilities are enabled through extensions to standard SQL.

For more details regarding these features of Oracle, see Chapter 13.

1.4.2.1 Oracle Text and interMedia

Oracle Text includes what was previously referred to as the
"ConText cartridge" with
Ultrasearch capabilities. It can identify the gist of a document by
searching for themes and key phrases in the document.

Oracle
interMedia
bundles additional image, audio, video, and locator functions and is
included in the database license. Oracle
interMedia offers the following capabilities:

The image portion of interMedia can store and
retrieve images.

The audio and video portions of interMedia can
store and retrieve audio and video clips, respectively.

The locator portion of interMedia can retrieve
data that includes spatial coordinate information.

1.4.2.2 Oracle Spatial Option

The Spatial option is available for Oracle Enterprise Edition. It can
optimize the display and retrieval of data linked to coordinates and
is used in the development of spatial information systems. Several
vendors of Geographic Information Systems (GIS)
products now bundle this option and leverage it as their search and
retrieval engine.

1.4.2.3 XML

Oracle added
native XML datatype support to the Oracle9i
database and XML and SQL interchangeability for searching.
The structured XML object is held natively in object relational
storage meeting the W3C DOM specification. The XPath syntax for
searching in SQL is based on the SQLX group specifications.