What Are Subprograms?
Subprograms are named PL/SQL blocks that can take parameters and be invoked. PL/SQL has two types of subprograms called procedures and functions. Generally, you use a procedure to perform an action and a function to compute a value.
Advantages of Subprograms
Subprograms provide extensibility; that is, they let you tailor the PL/SQL language to suit your needs.
Subprograms also provide modularity; that is, they let you break a program down into manageable, well-defined modules.
Finally, subprograms aid abstraction, the mental process of deriving a universal from particulars.
Understanding PL/SQL Procedures
A procedure is a subprogram that performs a specific action.
Understanding PL/SQL Functions
A function is a subprogram that computes a value. Functions and procedures are structured alike, except that functions have a RETURN clause.