So far, you have learned to write the most simplistic stored procedures possible, and you have learned to execute code. However, there is more to code execution than just full-blown stored procedures. In addition to full-blown procedures, PostgreSQL allows the use of anonymous code blocks. The idea is to run code that is needed only once. This kind of code execution is especially useful to deal with administrative tasks. Anonymous code blocks don't take parameters and are not permanently stored in the database as they don't have a name anyway.
Here is a simple example:
test=# DO $$ BEGIN RAISE NOTICE 'current time: %', now(); END; $$ LANGUAGE 'plpgsql'; NOTICE: current time: 2016-12-12 15:25:50.678922+01 ...
