Book Image

Learning PostgreSQL 10 - Second Edition

Book Image

Learning PostgreSQL 10 - Second Edition

Overview of this book

PostgreSQL is one of the most popular open source databases in the world, supporting the most advanced features included in SQL standards. This book will familiarize you with the latest features released in PostgreSQL 10. We’ll start with a thorough introduction to PostgreSQL and the new features introduced in PostgreSQL 10. We’ll cover the Data Definition Language (DDL) with an emphasis on PostgreSQL, and the common DDL commands supported by ANSI SQL. You’ll learn to create tables, define integrity constraints, build indexes, and set up views and other schema objects. Moving on, we’ll cover the concepts of Data Manipulation Language (DML) and PostgreSQL server-side programming capabilities using PL/pgSQL. We’ll also explore the NoSQL capabilities of PostgreSQL and connect to your PostgreSQL database to manipulate data objects. By the end of this book, you’ll have a thorough understanding of the basics of PostgreSQL 10 and will have the necessary skills to build efficient database solutions.
Table of Contents (23 chapters)
Title Page
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Customer Feedback
Preface

User-defined data types


PostgreSQL provides two methods for implementing user-defined data types through the following commands:

  • CREATE DOMAIN: The CREATE DOMAIN command allows developers to create a user-defined data type with constraints. This helps to make the source code more modular.
  • CREATE TYPE: The CREATE TYPE command is often used to create a composite type, which is useful in procedural languages, and is used as the return data type. Also, one can use the create type to create the ENUM type, which is useful to decrease the number of joins, specifically for lookup tables.

Often, developers tend not to use user-defined data types and use flat tables instead due to a lack of support on the driver side, such as JDBC and ODBC. Nonetheless, in JDBC, the composite data types can be retried as Java objects and parsed manually.

Domain objects, as with other database objects, should have a unique name within the schema scope. The first use case of domains is to use them for common patterns. For...