Before exploring the “meat and potatoes” of writing PL/SQL programs, you might benefit from some practical information about how to compile and run those programs. This chapter surveys a range of tools, in particular SQL*Plus, from which you can invoke your PL/SQL programs, and provides the specifics you’ll need to get started.
If you already have some experience with database programming, you probably realize that there are lots of different ways and places to use SQL (Structured Query Language). Well, the same is true for PL/SQL; not only can you invoke it from a variety of other languages, it can execute in two different runtime environments:
“Inside” the Oracle database server, as stored code. If you call PL/SQL from SQL*Plus, Java, or any other language, this is typically where it’s going to run.
In one of Oracle’s application development environments such as Oracle Forms or Oracle Reports, as a program that executes on a client computer. (Alternately, these tools can run on a “middle tier,” operated across the network from a browser-only or “thin” client.)
Let’s begin by looking at the first option, running on the Oracle server. Here you have additional options for the front end from which you launch your code. Some of the most popular programming tools include:
Oracle’s command-line tool, SQL*Plus, which connects to an Oracle server where you can run PL/SQL statements.
A host language such as C, C++, Java, Visual Basic, COBOL, Ada, ...