Extending the PostgreSQL Server with Custom Data Types

The customers table in this sample application contains a column named balance. I've made the assumption that the values in the balance column are expressed in local currency (that is, U.S. dollars in the U.S., British pounds in the U.K.). This assumption serves us well until our corner video store opens a web site and starts accepting orders from foreign customers.

PostgreSQL doesn't have a predefined data type that represents a foreign currency value, so let's create one. You want to store three pieces of information for each foreign currency value: the name of the currency (pounds, dollars, drachma, and so on), the number of units, and the exchange rate at the time the foreign currency value was created. Call your new data type FCUR (Foreign Currency). After you have fully defined the FCUR data type, you can create tables with FCUR columns, enter and display FCUR values, convert between FCUR values and other numeric types, and use a few operators (+,-,*,/) to manipulate FCUR values.

Part I: General PostgreSQL Use

Introduction to PostgreSQL and SQL

Working with Data in PostgreSQL

PostgreSQL SQL Syntax and Use

Performance

Part II: Programming with PostgreSQL

Introduction to PostgreSQL Programming

Extending PostgreSQL

PL/pgSQL

The PostgreSQL C APIlibpq

A Simpler C APIlibpgeasy

The New PostgreSQL C++ APIlibpqxx

Embedding SQL Commands in C Programsecpg

Using PostgreSQL from an ODBC Client Application

Using PostgreSQL from a Java Client Application

Using PostgreSQL with Perl

Using PostgreSQL with PHP

Using PostgreSQL with Tcl and Tcl/Tk

Using PostgreSQL with Python

Npgsql: The .NET Data Provider

Other Useful Programming Tools

Part III: PostgreSQL Administration

Introduction to PostgreSQL Administration

PostgreSQL Administration

Internationalization and Localization

Security

Replicating PostgreSQL Data with Slony

Contributed Modules

Index