Chapter 3. Your First PL/pgSQL Function
A function is the basic building block for extending PostgreSQL. A function accepts input in the form of parameters, and can create output in the form of output parameters or return values. Many functions are provided by PostgreSQL itself such as the common mathematical functions, for example, square root and absolute value. For a comprehensive list of what is already available, go to http://www.postgresql.org/docs/current/static/functions.html.
The functions that you create have all of the same privileges and power that the built-in functions possess. The developers of PostgreSQL use the same libraries to extend the database that you use as a developer to write your business logic.
This means that you have the tools available to be a first class citizen of the PostgreSQL development community. In fact, there are no second-class seats on this bus.
A function accepts parameters that can be of any data type available in PostgreSQL and it returns results...
