files, first we need to load configuration xml, because once we load the configuration file, automatically mapping file will be loaded as we registered this mapping xml in the configuration file.So to load configuration xml, we need to create object of in our program. update: It will persist the entity using an existing identifier. Detached objects can be reattached by calling session.merge() method of session class. Difference between load() and get() method in hibernate?They are linked to a Session so Hibernate knows what has changed. No persistent representation in the database and no identifier value have been assigned to an object. Hibernate Query Language isa powerful query language its syntax is quite similar to database SQL language,compared with SQL, however, HQL is fully object-oriented and understands notions like inheritance, polymorphism and association. These are persistent and not connected to the Session object. Check the detailed post about Hibernate Second level Cache – Eh Cache. But when you have a transient object, there is no session involved. And it will be destroyed by the garbage collector if the application does not hold a reference anymore. Example: Student student Obj = new Student (); student Name( €œKumar €); student Obj- transient object. HQL Select Query Example Query query = session.create Query(“from Student where student Name = ‘suresh’ “); 14. POJO(Plain Old Java Object)is a javabean that have defined setter and getter methods for all properties. These objects have the synchronized data with the database when the session was closed. In these cases you need to use merge for updates and persist for saviing. What are the Core interfaces of Hibernate framework? Session is a light weight and a non-thread safe and main function of the Session is to offer create, read and delete operations for instances of mapped entity classes. Decoupling the application code from the infrastructure frameworks is one of the many benefits of using POJOs. Version property is used in hibernate to know whether an object is in transient state or in detached state. Difference between the session.update() method and the session.lock() method? I didn’t cover all the concepts but i will cover rest of the concepts in part2 . Its purpose is to relieve the developer from a significant amount of relational data persistence-related programming tasks. Difference between different saving methods in Hibernate? merge Hibernate has following three Object states Transient, Detached and Persistant. load() method will throw an exception if the unique id is not found in the database but get() method will return null if the unique id is not found in the database. Difference between detached state and transient state Objects?
" xml (alternatively can use hibernate.properties): These two files are used to configure the hibernate sevice (connection driver class, connection URL, connection username, connection password, dialect etc).
Why hibernate is advantageous over Entity Beans & JDBC?
Ans: An entity bean always works under the EJB container, which allows reusing of the object external to the container.
If the object has an identifier already it will perform exclusively; it's much easier to let Hibernate decide what is new and what is old, especially in a more complex network of objects with mixed state.
The only (not really serious) disadvantage of exclusive at the database - for example, when a class is mapped with a natural composite key and no version or timestamp property.