Many, perhaps most, of the PL/SQL programs you write need to interact only with the underlying Oracle database using SQL. However, there will inevitably be times when you will want to send information from PL/SQL to the external environment or read information from some external source (screen, file, etc.) into PL/SQL. This chapter explores some of the most common mechanisms for I/O in PL/SQL, including the following built-in packages:
For displaying information on the screen
For reading and writing operating system files
For sending email from within PL/SQL
For retrieving data from a web page
It is outside the scope of this book to provide full reference information about the built-in packages introduced in this chapter. Instead, in this chapter, I will demonstrate how to use them to handle the most frequently encountered requirements. Check out Oracle’s documentation for more complete coverage. You will also find Oracle Built-in Packages (O’Reilly) a helpful source for information on many packages; several chapters from that book are available on this book’s web site.