Table Per Subclass using AnnotationAs we have specified earlier, in case of table per subclass strategy, tables are created as per persistent classes but they are treated using primary and foreign key. So there will not be any duplicate column in the relation. We need to specify @Inheritance(strategy=InheritanceType.JOINED) in the parent class and @PrimaryKeyJoinColumn annotation in the subclasses. Let's see the hierarchy of classes that we are going to map. The table structure for each table will be as follows: Table structure for Employee classTable structure for Regular_Employee classTable structure for Contract_Employee classExample of Table per subclass class using AnnotationIn this example we are creating the three classes and provide mapping of these classes in the employee.hbm.xml file. 1) Create the Persistent classesYou need to create the persistent classes representing the inheritance. Let's create the three classes for the above hierarchy: File: Employee.javaFile: Regular_Employee.javaFile: Contract_Employee.java2) Add project information and configuration in pom.xml file.Open pom.xml file and click source. Now, add the below dependencies between <dependencies>....</dependencies> tag. 3)Create the configuration fileOpen the hibernate.cgf.xml file, and add an entry of mapping resource like this: Now the configuration file will look like this: File: hibernate.cfg.xmlThe hbm2ddl.auto property is defined for creating automatic table in the database. 3) Create the class that stores the persistent objectIn this class, we are simply storing the employee objects in the database. File: StoreData.javaNext TopicCollection Mapping |