„One of the most powerful features of PostgreSQL is its support for user-defined functions written in various programming languages, including pure SQL, C, Perl, Python, and PHP. Perhaps the most common programming language for PostgreSQL functions, however, is PL/pgSQL (don’t ask me to pronounce it), because it comes with PostgreSQL and is easy to set up.
PL/pgSQL is a procedural language similar to Oracle’s PL/SQL. It’s much more powerful than pure SQL in that it supports variables, conditional expressions, looping constructs, exceptions, and the like. Because it natively supports all of PostgreSQL’s SQL syntax, you can consider it a superset of PostgreSQL SQL. It also respects all data types and their associated functions and operators, and is completely safe for use inside of the server. „