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Posted Mar 9, 2005

Oracle and Pro*C - Part 1

By Steve Callan

Pro*C is another one of those tools or features from Oracle that keeps a low profile, quietly waiting its turn for you to use it when the need arises. With a little searching on various Oracle-related Web sites, you can read about how others have used Pro*C to greatly reduce processing time for some operation or procedure. One of C's features, being a compiled language, is its processing speed. You may find yourself in a situation where Oracle lacks the heavy duty processing speed you need, but at the same time, find that your external application (written in C or C++) lacks the data processing capabilities of Oracle.

What is Pro*C? The Pro*C/C++ Precompiler Getting Started for Windows guide found in the Oracle documentation library starts off with this very question.

The Pro*C/C++ precompiler enables you to create applications that access your Oracle database whenever rapid development and compatibility with other systems are your priorities.

The Pro*C/C++ programming tool enables you to embed Structured Query Language (SQL) statements in a C or C++ program. The Pro*C/C++ precompiler translates these statements into standard Oracle runtime library calls, then generates a modified source program that you can compile, link, and run in the usual way.

Another key reference book is the Pro*C/C++ Precompiler Programmer's Guide, and it lists some reasons why you want to use Pro*C. Some of the reasons are shown below.

The Oracle Pro*C/C++ Precompiler lets you use the power and flexibility of SQL in your application programs. A convenient, easy to use interface lets your application access Oracle directly.

Unlike many application development tools, Pro*C/C++ lets you create highly customized applications. For example, you can create user interfaces that incorporate the latest windowing and mouse technology. You can also create applications that run in the background without the need for user interaction.

Furthermore, Pro*C/C++ helps you fine-tune your applications. It allows close monitoring of resource use, SQL statement execution, and various runtime indicators. With this information, you can change program parameters for maximum performance.

Where is Pro*C and How Do You Get It?

I will use the Windows platform as an example throughout the remainder of this article. After a typical installation of Oracle software, there will be a directory named precomp under ORACLE_HOME. Within precomp, you will see several other subdirectories. If you want to use the sample programs, you will have to restart Oracle Universal Installer and perform a custom installation. The place you are looking for is in the development tools section.

Once you get to the Available Product Components section, select Oracle Programmer (the option may show Reinstall; the screen shot shows Installed because I have already reinstalled this component).

Continue with the installation (it takes a few minutes) and then exit the installer. Look in the precomp directory, and under it, in the demo\proc directory. You should see quite a few folders similar to those shown below.

The getting started for Windows guide includes a description of each demo program. The demos generally require the Scott/Tiger schema to be in place, so rebuild that if you have to (running ORACLE_HOME\rdbms\admin\utlsampl.sql is one way). Some of the demos require additional scripts to be run, so check Table 3-1 as needed.

What Else Do You Need?

The files you use with Pro*C are "pc" files, and if you are familiar with C or C++, you are probably looking for .c or .cpp files. They are there, kind of sort of. After running the precompiler, a .c or .cpp file is created, depending on what you asked for (we will be using .c). Once the .c file is created, you can compile the file in a normal fashion to create the executable. If on UNIX, the make command is used, and on Windows, you can use, for example, Microsoft Visual C++ 6.0, and that answers the "what else do you need" question. How do you get Visual C++ (or Visual Studio)? Many C or C++ textbooks (the Deitel and Deitel series for one) provide a limited or introductory version of Visual C++, and for learning purposes, that is all you need for your Pro*C adventure.

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