Category: Object Relationship Mapping

Hibernate is a powerful, high performance object/relational persistence and query service. This lets the users to develop persistent classes following object-oriented principles such as association, inheritance, polymorphism, composition, and collections.

Associations that are related to container management persistence are called managed associations. These are bi-directional associations. Coming to hibernate associations, these are unidirectional.

Inheritance hierarchy is represented as below. Table per concrete class. Table per class hierarchy. Table per subclass.

There are three methods by which an object can be identified. Object identity – Objects are identical if they reside in the same memory location in the JVM. This can be checked by using...

XDoclet has brought the concept of attribute-oriented programming to Java. Until JDK 1.5, the Java language had no support for annotations; now XDoclet uses the Javadoc tag format (@attribute) to specify class-, field-, or...

– Typical and most common property mapping <property name="description" column="DESCRIPTION" type="string"/> Or <property name="description" type="string"> <column name="DESCRIPTION"/> </property> – Derived properties <property name="averageBidAmount" formula="( select AVG(b.AMOUNT) from BID b where b.ITEM_ID = ITEM_ID )"...

HQL stands for Hibernate Query Language. Hibernate allows the user to express queries in its own portable SQL extension and this is called as HQL. It also allows the user to express in native...

ORM tools require a metadata format for the application to specify the mapping between classes and tables, properties and columns, associations and foreign keys, Java types and SQL types. This information is called the...

There are mainly two types of environments in which the configuration of hibernate application differs. i. Managed environment – In this kind of environment everything from database connections, transaction boundaries, security levels and all...

The name of the file should be like this : filename.hbm.xml The filename varies here. The extension of these files should be “.hbm.xml”. This is just a convention and it’s not mandatory. But this...