You already know how to interact with the database using SQL, but it is not sufficient
for building enterprise applications. PL/SQL is a third generation language that has
the expected procedural and namespace constructs, and its tight integration with SQL
makes it possible to build complex and powerful applications. Because PL/SQL is
executed in the database, you can include SQL statements in your code without
having to establish a separate connection.

The main types of program units you can create with PL/SQL and store in the
database are standalone procedures and functions, and packages. Once stored in the
database, these PL/SQL components, collectively known as stored procedures, can be
used as building blocks for several different applications.

While standalone procedures and functions are invaluable for testing pieces of
program logic, Oracle recommends that you place all your code inside a package.
Packages are easier to port to another system, and have the additional benefit of
qualifying the names of your program units with the package name. For example, if
you developed a schema-level procedure called

continue

in a previous version of

Oracle Database, your code would not compile when you port it to a newer Oracle
Database installation. This is because Oracle recently introduced the statement

CONTINUE

that exits the current iteration of a loop and transfers control to the next

iteration. If you developed your procedure inside a package, the procedure package_
name

.continue

would have been protected from such name capture.