Dirty checking feature of the Hibernate allows users or developers to avoid time consuming data base write actions. This feature makes necessary updations and changes to the fields which require a change, remaining fields are left unchanged or... Read More

Hibernate is a pure Java object-relational mapping (ORM) and persistence framework that allows you to map plain old Java objects to relational database tables using (XML) configuration files.Its purpose is to relieve the developer from a... Read More

hibernate Vs. JDBC :- JDBC Hibernate With JDBC, developer has to write code to map an object model's data representation to a relational data model and its corresponding database schema. Hibernate is flexible and powerful ORM solution to map... Read More

The general flow of Hibernate communication with RDBMS is : * Load the Hibernate configuration file and create configuration object. It will automatically load all hbm mapping files * Create session factory from configuration object * Get one... Read More

Named SQL queries are defined in the mapping xml document and called wherever required. Example: <sql-query name = "empdetails"> <return alias="emp" class="com.test.Employee"/> SELECT emp.EMP_ID AS {emp.empid}, emp.EMP_ADDRESS AS ... Read More

An ORM solution consists of the followig four pieces: * API for performing basic CRUD operations * API to express queries refering to classes * Facilities to specify metadata * Optimization facilities : dirty checking, lazy associations... Read More

Criteria is a simplified API for retrieving entities by composing Criterion objects. This is a very convenient approach for functionality like "search" screens where there is a variable number of conditions to be placed upon the result set. *... Read More

The ORM levels are: * Pure relational (stored procedure.) * Light objects mapping ( JDBC) * Medium object mapping * Full object Mapping (composition,inheritance, polymorphism, persistence by reachability) Read More

* First we need to write Java domain objects (beans with setter and getter). * Write hbm.xml, where we map java class to table and database columns to Java class variables. Example : <hibernate-mapping> <class name="com.test... Read More

The application obtains Session instances from a SessionFactory. There is typically a single SessionFactory for the whole application?created during application initialization. The SessionFactory caches generate SQL statements and other mapping... Read More

Callback interfaces allow the application to receive a notification when something interesting happens to an object?for example, when an object is loaded, saved, or deleted. Hibernate applications don't need to implement these callbacks, but... Read More

These methods are the most convenient to use in hibernate. These methods allow you to load all your Hibernate documents at a time. These methods simplify code configuration, refactoring, layout, etc. These functions help you to add your hibernate... Read More

Hibernate can be configured with two types of files out of which hibernate.cfg.xml is widely used and popular feature. Hibernate consults hibernate.cfg.xml file for its operating properties such as database dialect, connection string and mapping... Read More

<sql-query name="selectAllEmployees_SP" callable="true"> <return alias="emp" class="employee"> <return-property name="empid" column="EMP_ID"/> <return-property name="name" column="EMP_NAME"/> <return-property name=... Read More

Criteria is a simplified API for retrieving entities by composing Criterion objects. This is a very convenient approach for functionality like "search" screens where there is a variable number of conditions to be placed upon the result set. Example ... Read More

Using Hibernate SQL Dialects , we can switch databases. Hibernate will generate appropriate hql queries based on the dialect defined. Read More

sorted collection vs. order collection :- sorted collection order collection A sorted collection is sorting a collection by utilizing the sorting features provided by the Java collections framework. The sorting occurs in the memory of JVM which... Read More

Three types of instance states: * Transient -The instance is not associated with any persistence context * Persistent -The instance is associated with a persistence context * Detached -The instance was associated with a persistence context which... Read More

cascade - enable operations to cascade to child entities. cascade="all|none|save- update|delete|all-delete-orphan" inverse - mark this collection as the "inverse" end of a bidirectional association. inverse=" true|false" Essentially "inverse"... Read More

The Session interface is the primary interface used by Hibernate applications. It is a single-threaded, short-lived object representing a conversation between the application and the persistent store. It allows you to create query objects to retrieve... Read More

Mark the class as mutable="false" (Default is true),. This specifies that instances of the class are (not) mutable. Immutable classes, may not be updated or deleted by the application. Read More

Hibernate uses a sophisticated algorithm to determine an efficient ordering that avoids database foreign key constraint violations but is still sufficiently predictable to the user. This feature is called transactional write-behind. Read More

* Bag * Set * List * Array * Map Read More

Creating Database applications with Java is made simpler with Hibernate. First Plain old java object needs to be written, XML mapping file should be created which shows relationship between database and class attributes. Hibernate APIs can be used... Read More

When a Sessions save () is passed to a transient mapped object it makes the method to become more persistent. Garbage collection and termination of the Java virtual machine stays as long as it is deleted explicitly. It may head back to its... Read More

There are three types of inheritance models in Hibernate: * Table per class hierarchy * Table per subclass * Table per concrete class Read More

Use update() if you are sure that the session does not contain an already persistent instance with the same identifier, and merge() if you want to merge your modifications at any time without consideration of the state of the session. Read More

The proxy attribute enables lazy initialization of persistent instances of the class. Hibernate will initially return CGLIB proxies which implement the named interface. The actual persistent object will be loaded when a method of the proxy is... Read More

org.springframework.orm.hibernate.HibernateTemplate is a helper class which provides different methods for querying/retrieving data from the database. It also converts checked HibernateExceptions into unchecked DataAccessExceptions. Read More

In Hibernate configuration file set as follows: <property name="show_sql">true</property> Read More

HQL provides four ways of expressing (inner and outer) joins:- * An implicit association join * An ordinary join in the FROM clause * A fetch join in the FROM clause. * A theta-style join in the WHERE clause. Read More

This function translates a Java class name into file name. This translated file name is then loaded as an input stream from the Java class loader. This addclass function is important if you want efficient usage of classes in your code. Read More

It creates new hibernate sessions by referencing immutable and thread safe objects. Application using hibernate are usually allowed and desgined to implement single instance of the class using this interface. Only single instance of a class can be... Read More

The five core interfaces are used in just about every Hibernate application. Using these interfaces, you can store and retrieve persistent objects and control transactions. * Session interface * SessionFactory interface * Configuration... Read More

Hibernate offers a query language that embodies a very powerful and flexible mechanism to query, store, update, and retrieve objects from a database. This language, the Hibernate query Language (HQL), is an object-oriented extension to SQL. Read More

Using <generator> tag. Example:- <id column="USER_ID" name="id" type="java.lang.Long"> <generator class="sequence"> <param name="table">SEQUENCE_NAME</param> <generator> </id> Read More

* A component is an object saved as a value, not as a reference * A component can be saved directly without needing to declare interfaces or identifier properties * Required to define an empty constructor * Shared references not supported Read More

By mapping the property with access="field" in Hibernate metadata. This forces hibernate to bypass the setter method and access the instance variable directly while initializing a newly loaded object. Read More

Primary feature of hibernate is to java classes to database tables. Data query and retrieval is also possible with Hibernate. Application portability is a key feature in Hibernate it allows developers to port applications to almost all SQL... Read More

Hibernate Vs EJB 3.0 :-<br>Hibernate EJB 3.0 <br>Session?Cache or collection of loaded objects relating to a single unit of work Persistence Context-Set of entities that can be managed by a given EntityManager is defined by a persistence... Read More

Hibernate solves problems such as Object Relational impedance mismatch, etc. It is commonly used for object and query service. It helps data base developers develop classes which include inheritance, association, composition and polymorphism. A... Read More

ORM stands for object/relational mapping. ORM is the automated persistence of objects in a Java application to the tables in a relational database. Read More

The main advantage of ORM like hibernate is that it shields developers from messy SQL. Apart from this, ORM provides following benefits: * Improved productivity o High-level object-oriented API o Less Java code to write o No SQL to write ... Read More

Hibernate simplifies: * Saving and retrieving your domain objects * Making database column and table name changes * Centralizing pre save and post retrieve logic * Complex joins for retrieving related items * Schema creation from object model ... Read More

The most common methods of Hibernate configuration are: * Programmatic configuration * XML configuration (hibernate.cfg.xml) Read More

load() vs. get() :- load() get() Only use the load() method if you are sure that the object exists. If you are not sure that the object exists, then use one of the get() methods. load() method will throw an exception if the unique id is not... Read More

Transparent persistence is provided for Plain old Java objects or POJOs. For proper functioning of the applications importance should be given to the methods equals () and hash Code methods (). It has a requirement which should be strictly followed... Read More

The benefits of HibernateTemplate are : * HibernateTemplate, a Spring Template class simplifies interactions with Hibernate Session. * Common functions are simplified to single method calls. * Sessions are automatically closed. * Exceptions are... Read More

This represents hibernate session which perform the manipulation on the database entities. Some of the activities performed by session interface are as follows they are managing the persistence state, fetching persisted ones and management of the... Read More

The properties that are not mapped to a column, but calculated at runtime by evaluation of an expression are called derived properties. The expression can be defined using the formula attribute of the element. Read More

Mapping description file is the second file which Hibernate uses to configure its functions. This mapping file has an extension *.hbm which instructs mapping between Java class and database tables. The usage of mapping description file rests entirely... Read More

Transactions denote a work file which can save changes made or revert back the changes. A transaction can be started by session.beginTransaction() and it uses JDBC connection, CORBA or JTA. When this session starts several transactions may occur. Read More

Mapping files forms the core of any database mapping tools. These files contain field to field mapping, usually this mapping occurs between classes and attributes. After mapping files they can be persist to the database. Tags can be used to indicate... Read More

A fetching strategy is the strategy Hibernate will use for retrieving associated objects if the application needs to navigate the association. Fetch strategies may be declared in the O/R mapping metadata, or over-ridden by a particular HQL or... Read More

Application level data integrity constants are important if you are making changes to offline information which is again backed by database. Higher level locking or versioning protocol is required to support them. Version field usage comes at this... Read More

Automatic dirty checking is a feature that saves us the effort of explicitly asking Hibernate to update the database when we modify the state of an object inside a transaction. Read More

Some of the advantages which a developer can get from Hibernate are as follows: - Mapping of one POJO table to one table is not required in hibernate. It supports inheritance relationships and is generally a fast tool. Portability is necessary the... Read More

This id field corresponds to the surrogate key which is generated by the database. These fields are handled by the id field. Name attribute is used to specify the names of the field and it should correspond to the method name of getid. This also... Read More