A function is the basic building block for extending PostgreSQL. A function accepts input in the form of parameters, and it can create output in the form of output parameters or return values. Many functions are provided by PostgreSQL itself, that is, common mathematical functions such as square roots and absolute values. For a comprehensive list of the functions that are already available, go to http://www.postgresql.org/docs/current/static/functions.html.

The functions that you create have the same privileges and ability 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...