Hibernate

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Introduction

ORM goal: Take advantage of the things SQL databases do well, without leaving the Java language of objects and classes.

ORM real goal: Do less work and have a happy DBA.

Hibernate is an open-source ORM toolkit for the Java language, providing a framework for mapping an object-oriented domain model to a traditional relational database.

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Hibernate Architecture

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XML

XML (Extensible Markup Language) is a human readable way of describing structured data.

XML is made up of tags enclosing text:<dataset>

<record><name>David</name><age>47</age>

</record></dataset>

Mapping Java classes to database table is accomplished through the configuration of an XML file.

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SQL

SQL (Structured Query Language) is a standard language for accessing and manipulating relational databases.

SQL queries allow the user to specify a description of the desired result set:

SELECT title, price

FROM Book

WHERE price > 100.00

ORDER BY title

SQL is designed for the retrieval and management of data in database and database schema creation and modification.

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Hibernate query options

• Hibernate Query Language (HQL)• “minimal” object-oriented dialect of ANSI SQL

• Criteria Queries (QBC)• extensible framework for query objects• includes Query By Example (QBE)

• Native SQL queries• SQL queries may be defined and called exactly HQL

query

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Hibernate Features

• Persistence for POJOs (JavaBeans)

• Flexible and intuitive mapping

• Support for fine-grained object models

• Powerful, high performance queries

• Dual-Layer Caching Architecture (HDLCA)

• Lazy loading

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