This chapter introduces PL/SQL, its origins, and its various versions. It also offers a guide to additional resources for PL/SQL developers and some words of advice.
PL/SQL stands for “Procedural Language extensions to the Structured Query Language.”SQL is the now-ubiquitous language for both querying and updating—never mind the name—of relational databases. Oracle Corporation introduced PL/SQL to overcome some limitations in SQL and to provide a more complete programming solution for those who sought to build mission-critical applications to run against the Oracle database.
PL/SQL has several defining characteristics:
- It is a highly structured, readable, and accessible language
Modeled after the Ada language, PL/SQL incorporates some of the latest and greatest in language design. If you are new to programming, PL/SQL is a great place to start. If you are experienced in other programming languages, you will very easily adapt to the new syntax. The accessibility of PL/SQL also means that you can write code that is easily maintained and enhanced over time, a critical aspect of high-quality software development.
- PL/SQL is a standard and portable language for Oracle development
If you write a PL/SQL procedure or function to execute from within the Personal Oracle database sitting on your laptop, you can move that same procedure to a database on your corporate network and execute it there without any changes (assuming compatibility of Oracle versions, of course!). “Write once, run everywhere” was the mantra of PL/SQL long before Java appeared. For PL/SQL, though, “everywhere” means “everywhere there is an Oracle database.”
- PL/SQL is an embedded language
PL/SQL was not designed to be used as a “standalone” language, but instead to be invoked from within a “host” environment. So, for example, you can run PL/SQL programs from within the database (through, say, the SQL*Plus interface). Alternatively, you can define and execute PL/SQL programs from within an Oracle Developer form or report (this approach is called client-side PL/SQL ). You cannot, however, create a PL/SQL “executable” that runs all by itself. Chapter 2 provides all the information you need to get up and running with this embedded language.
- PL/SQL is a high-performance, highly integrated database language
These days, you have a number of choices when it comes to writing software to run against the Oracle database. You can use Java and JDBC (or SQLJ); you can use Visual Basic and ODBC; you can go with Delphi, C++, and so on. You will find, however, that it is easier to write highly efficient code to access the Oracle database in PL/SQL than it is in any other language. In particular, Oracle offers certain PL/SQL-specific enhancements such as the FORALL statement that can improve database performance by an order of magnitude or more.
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