Using PL/SQL to Create Web Applications and Server Pages

Using PL/SQL to Create Web Applications and Server Pages

You can use PL/SQL to develop Web applications or server pages. These are briefly described in this section. For detailed information on using PL/SQL to create Web applications, see "Developing Applications with the PL/SQL Web Toolkit" in Oracle Database Application Developer's Guide - Fundamentals. For detailed information on using PL/SQL to create Web Server Pages (PSPs), see "Developing PL/SQL Server Pages" in Oracle Database Application Developer's Guide - Fundamentals.

PL/SQL Web Applications

With PL/SQL you can create applications that generate Web pages directly from an Oracle database, allowing you to make your database available on the Web and make back-office data accessible on the intranet.

The program flow of a PL/SQL Web application is similar to that in a CGI Perl script. Developers often use CGI scripts to produce Web pages dynamically, but such scripts are often not optimal for accessing Oracle Database. Delivering Web content with PL/SQL stored procedures provides the power and flexibility of database processing. For example, you can use DML, dynamic SQL, and cursors. You also eliminate the process overhead of forking a new CGI process to handle each HTTP request.

You can implement a Web browser-based application entirely in PL/SQL with PL/SQL Gateway and the PL/SQL Web Toolkit.

■PL/SQL gateway enables a Web browser to invoke a PL/SQL stored procedure through an HTTP listener. mod_plsql, one implementation of the PL/SQL gateway, is a plug-in of Oracle HTTP Server and enables Web browsers to invoke PL/SQL stored procedures.

■PL/SQL Web Toolkit is a set of PL/SQL packages that provides a generic interface to use stored procedures called by mod_plsql at runtime.

PL/SQL Server Pages

PL/SQL Server Pages (PSPs) enable you to develop Web pages with dynamic content. They are an alternative to coding a stored procedure that writes out the HTML code for a web page, one line at a time.

Using special tags, you can embed PL/SQL scripts into HTML source code. The scripts are executed when the pages are requested by Web clients such as browsers. A script can accept parameters, query or update the database, then display a customized page showing the results.

During development, PSPs can act like templates with a static part for page layout and a dynamic part for content. You can design the layouts using your favorite HTML authoring tools, leaving placeholders for the dynamic content. Then, you can write the PL/SQL scripts that generate the content. When finished, you simply load the resulting PSP files into the database as stored procedures.

Summary of PL/SQL Built-In Functions

PL/SQL provides many powerful functions to help you manipulate data. These built-in functions fall into the following categories:

Error reporting

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Summary of PL/SQL Built-In Functions

Number

Character

Datatype conversion

Date

Object reference

Miscellaneous

Table 2–4 shows the functions in each category. For descriptions of the error-reporting functions, see "SQLCODE Function" on page 13-117 and "SQLERRM Function" on page 13-118. For descriptions of the other functions, see Oracle Database SQL Reference.

Except for the error-reporting functions SQLCODE and SQLERRM, you can use all the functions in SQL statements. Also, except for the object-reference functions DEREF, REF, and VALUE and the miscellaneous functions DECODE, DUMP, and VSIZE, you can use all the functions in procedural statements.

Although the SQL aggregate functions (such as AVG and COUNT) and the SQL analytic functions (such as CORR and LAG) are not built into PL/SQL, you can use them in SQL statements (but not in procedural statements).

Fundamentals of the PL/SQL Language 2-39

Summary of PL/SQL Built-In Functions

Table 2–4 Built-In Functions

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