About Packages

A package is a PL/SQL unit that consists of related subprograms and the explicit cursors and variables that they use.

Oracle recommends that you put your subprograms into packages. Some of the reasons are:

• Packages allow you to hide implementation details from client programs.

  Hiding implementation details from client programs is a widely accepted best practice. Many Oracle customers follow this practice strictly, allowing client programs to access the database only by calling PL/SQL subprograms. Some customers allow client programs to use SELECT statements to retrieve information from database tables, but require them to call PL/SQL subprograms for all business functions that change the database.

• Packaged subprograms must be qualified with package names when invoked, which ensures that their names will always work.

  For example, suppose that you developed a schema-level procedure named CONTINUE before Oracle Database 11g Release 1 (11.1). Release 11.1 introduced the CONTINUE statement. Therefore, if you ported your code to 11.1, it would no longer compile. However, if you had developed your procedure inside a package, your code would refer to the procedure as package_name.CONTINUE, so the code would still compile.

• Packaged subprograms can send and receive records and collections.

  Standalone stored subprograms can send and receive only scalar parameters—single values with no internal components, such as VARCHAR2, NUMBER, and DATE.