Book Image

PostgreSQL Development Essentials

By : Baji Shaik
Book Image

PostgreSQL Development Essentials

By: Baji Shaik

Overview of this book

PostgreSQL is the most advanced open source database in the world. It is easy to install, configure, and maintain by following the documentation; however, it’s difficult to develop applications using programming languages and design databases accordingly. This book is what you need to get the most out of PostgreSQL You will begin with advanced SQL topics such as views, materialized views, and cursors, and learn about performing data type conversions. You will then perform trigger operations and use trigger functions in PostgreSQL. Next we walk through data modeling, normalization concepts, and the effect of transactions and locking on the database. The next half of the book covers the types of indexes, constrains, and the concepts of table partitioning, as well as the different mechanisms and approaches available to write efficient queries or code. Later, we explore PostgreSQL Extensions and Large Object Support in PostgreSQL. Finally, you will perform database operations in PostgreSQL using PHP and Java. By the end of this book, you will have mastered all the aspects of PostgreSQL development. You will be able to build efficient enterprise-grade applications with PostgreSQL by making use of these concepts
Table of Contents (17 chapters)
PostgreSQL Development Essentials
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface

Anomalies in DBMS


Broadly, we have three types of anomalies that will occur when the database is not normalized. These are the insertion, update, and deletion anomalies. Let's consider each one of them with an example.

For example, suppose a company stores employee details in a table named employee that has four attributes: emp_id to store the employee's id, emp_name to store the employee's name, emp_address to store the employee's address, and emp_dept to store the department details (where the employee works). At the initial stage, the table will look like this:

emp_id

emp_name

emp_address

emp_dept

101

Roger

Texas

D001

101

Roger

Texas

D002

123

Martin

Ohio

D890

166

George

New York

D900

166

George

New York

D004

As you can see, the preceding table is not normalized. We will start to see the following problems when a table is not normalized:

  • Update anomaly: In the preceding table, we have two rows for employee George as...