If you are looking for a book on Postgresql the Douglas book http://www.amazon.com/PostgreSQL-Developers-Library-Korry-Do... is pretty good introduction to most of the topics specific to postgres, it includes a sample implementation of a postgres accessing script in most of the languages commonly used for the task, which can be a bit repetitive (perl, python, php, java, C, same tune different instrument) but that does make it a fairly good reference.