Book Image

NHibernate 2 Beginner's Guide

By : Aaron Cure
Book Image

NHibernate 2 Beginner's Guide

By: Aaron Cure

Overview of this book

<p>NHibernate is an open source object-relational mapper, or simply put, a way to retrieve data from your database into standard .NET objects. Quite often we spend hours designing the database, only to go back and re-design a mechanism to access that data and then optimize that mechanism. This book will save you time on your project, providing all the information along with concrete examples about the use and optimization of NHibernate.<br /><br />This book is an approachable, detailed introduction to the NHibernate object-relational mapper and how to integrate it with your .NET projects. If you're tired of writing stored procedures or maintaining inline SQL, this is the book for you.<br /><br />Connecting to a database to retrieve data is a major part of nearly every project, from websites to desktop applications to distributed applications. Using the techniques presented in this book, you can access data in your own database with little or no code.<br /><br />This book covers the use of NHibernate from a first glance at retrieving data and developing access layers to more advanced topics such as optimization and Security and Membership providers. It will show you how to connect to multiple databases and speed up your web applications using strong caching tools. We also discuss the use of third-party tools for code generation and other tricks to make your development smoother, quicker, and more effective.</p>
Table of Contents (19 chapters)
NHibernate 2
Credits
About the Author
About the Reviewers
Preface
Index

Why do we call .Commit()?


I'm sure you are wondering why we keep calling .Commit() after we call .Save(). Basically, .Commit() closes our transaction and synchronizes the cached objects with the database.

We'll talk more about caching later, but in its simplest configuration, NHibernate uses a first level cache (or the session cache) to store objects. When you first query an object from the database, it is placed into this cache.

If you haven't told NHibernate to update or delete an object from the database, and it has already been cached, then it will pull this object from the cache rather than round-tripping to the database, improving performance.

By calling .Commit(), we let NHibernate know that we have updated the record(s) in the transaction and that it should persist them to the database.