You will want to take maximum possible advantage of builtin and prebuilt packages. Soon, however, you will be building your own packages. This section explores syntax and issues related to package construction.
Remember that a package consists of up to two distinct parts: the specification and the body. The specification and body are completely distinct objects. You can write and compile the specification independently of the body. When you create and replace stored packages in the database, you perform this action separately for each specification and each body. The package specification describes the different elements of the package that can be called or referenced. The package body contains the implementation or executable code for the elements of the specification.
This chapter has already introduced to you the package specification. Before turning our attention to the package body, let's examine the circumstances under which you should consider building your own package.
When should you build a package, instead of just creating a set of standalone procedures and functions? Anyone who has attended any of my classes or presentations could probably guess my answer (or is it my dogma): Always! You should always build a package! A package is the answer to all of your problems in PL/SQL!
I do realize that my readers deserve a more reasoned and nuanced answer. So I'll review the reasons for building a package. ...