Book Image

Spring Persistence with Hibernate

By : Ahmad Seddighi
Book Image

Spring Persistence with Hibernate

By: Ahmad Seddighi

Overview of this book

<p>Spring is the leading platform to build and run enterprise Java applications. Spring's Hibernate integration makes it easy to mix and match persistence methodologies simplifying your Hibernate applications. You can incorporate lots of Inversion of Control (IoC) convenience features to address many typical Hibernate integration issues, making this integration all the more favorable for your application. <br /><br />This easy-to-use book will turn the complex-sounding integration into a straightforward walk-through. Persistence is important for creating a data access-based transactions tier, central to financial, insurance, and banking applications. You will be able to enhance your applications using the most common, advanced, and optional features of Hibernate.<br /><br />This book starts with the philosophy and the brief history of persistence. It provides an introduction to how persistence frameworks and technologies came into the development scene and what problems they are aimed to solve.<br /><br />The book continues with a discussion about Hibernate as the most popular persistence framework in Java. First, you will learn how to get Hibernate and add it to a project and how to configure it before it can be used. Next, you will get an in-depth knowledge about Hibernate and understand the essential concepts behind persistence with Hibernate and more. When Hibernate has been fully discussed, you will get to know Spring as another popular framework in Java, and have a look at essential features of Spring and its added value for Hibernate-based projects. Finally the book will provide a comprehensive discussion about using Hibernate with Spring and the problems that are solved with Spring.</p>
Table of Contents (22 chapters)
Spring Persistence with Hibernate
Credits
About the Author
About the Reviewer
Preface
Index

HQL


As mentioned earlier, HQL is an SQL-like, Hibernate-specific, and database independent language used to query persisted objects from the back-end rational database. Since Hibernate handles many relational storage issues, and solves the relevant problems when mapping the object-oriented world to the relational world, HQL is a great substitute for SQL when you're developing the object-oriented application which interacts with a relational database through Hibernate.

HQL is not a substitute for SQL. Rather, it lets us express our queries in an object-oriented form. When an HQL expression is executed, it is first transformed into an SQL statement. The generated SQL is then executed against the database, the result is placed in persistent objects, and the objects are returned to the application. The following figure depicts this scenario:

The from clause

In its simplest form, an HQL expression consists of a from clause that ends with the name of a particular persistent class. Here is an example...