How to map Composite Primary Key to Entity Class in JPA Hibernate

In this example I am going to tell you how to map composite primary key to entity class in your JPA Hibernate entity class. Composite primary key is a combination of two or more columns made together as a primary key. Therefore the combination of column values will be as a unique instead of having a single column value as unique. Let’s say you have created a table called user in your database and the user table has three columns – id, name and email. So you don’t want to…

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Java and XML based JPA Persistence Unit Configurations

Here in this tutorial I am going to tell you how to configure Persistence Unit for JPA (Java Persistence API). Here I am going to show you both XML and Java based configurations for persistence unit in JPA. This is a pure Java application and I am not using Spring framework for this example. A persistence unit defines the details that are required when you acquire an entity manager. To package your EclipseLink JPA application, you must configure the persistence unit during the creation of the persistence.xml file. Define each…

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What is the use of @Temporal annotation in JPA

In this tutorial I am going to tell you what is the use of @Temporal annotation in JPA (Java Persistence API). @Temporal is a JPA annotation and generally specified only for persistent fields or properties of type java.util.Date and java.util.Calendar. Generally you use @Temporal annotation on the date or calendar field in entity classes while you are mapping database table and Java classes where Hibernate is used as an ORM (Object Relational Mapping) framework. You won’t be able to apply @Temporal annotation on Java 8 date time API. If you try…

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JPA Criteria API

Introduction This tutorial will show you how to use JPA(Java Persistence API) Criteria API Queries for selecting data from database. The Java Persistence API (JPA) is a Java specification for accessing, persisting, and managing data between Java objects / classes and a relational database. The Criteria API is used to define queries for entities and their persistent state by creating query-defining objects. Criteria API queries are written using Java programming language APIs, are typesafe, and are portable. Such queries work regardless of the underlying data store.

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Many to Many Mapping in JPA

In this example I am going to show you how we can implement Many to Many(@ManyToMany) relationship using JPA persistence API in Java. The Java Persistence API (JPA) is a Java specification for accessing, persisting, and managing data between Java objects / classes and a relational database. The JPA is used to reduce the burden of writing codes for relational object management, a programmer or developer follows the ‘JPA Provider’ framework, which allows easy interaction with database instance. The JPA being a Java framework a programmer also needs not to…

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One to One Mapping in JPA

In this example I am going to show you how we can implement One to One(@OneToOne) relationship using JPA persistence API in Java. The Java Persistence API (JPA) is a Java specification for accessing, persisting, and managing data between Java objects / classes and a relational database. The JPA is used to reduce the burden of writing codes for relational object management, a programmer or developer follows the ‘JPA Provider’ framework, which allows easy interaction with database instance. The JPA being a Java framework a programmer also needs not to…

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One to Many Mapping in JPA

In this example I am going to show you how we can implement One to Many(@OneToMany) relationship using JPA persistence API in Java. The Java Persistence API (JPA) is a Java specification for accessing, persisting, and managing data between Java objects / classes and a relational database. The JPA is used to reduce the burden of writing codes for relational object management, a programmer or developer follows the ‘JPA Provider’ framework, which allows easy interaction with database instance. The JPA being a Java framework a programmer also needs not to…

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Many to One Mapping in JPA

In this example I am going to show you how we can implement Many to One(@ManyToOne) relationship using JPA persistence API in Java. The Java Persistence API (JPA) is a Java specification for accessing, persisting, and managing data between Java objects / classes and a relational database. The JPA is used to reduce the burden of writing codes for relational object management, a programmer or developer follows the ‘JPA Provider’ framework, which allows easy interaction with database instance. The JPA being a Java framework a programmer also needs not to…

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JPA Inheritance Strategy : Table Per Concrete Class Hierarchy (TABLE_PER_CLASS)

JPA comes with a provision to create tables and populate them as per the Java classes involved in inheritance. JPA offers basically three different approaches to map hierarchical classes – classes involved in inheritance with database tables. Observe, in the above hierarchy, three classes are involved where Person is the super class and Student and Teacher are sub-classes with their own properties declared as instance variables. Now the question is how many tables are required and moreover how to link the tables so that Student gets three properties of id…

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JPA Inheritance Strategy : Table Per Sub-Class Hierarchy (JOINED)

JPA comes with a provision to create tables and populate them as per the Java classes involved in inheritance. JPA offers basically three different approaches to map hierarchical classes – classes involved in inheritance with database tables. Observe, in the above hierarchy, three classes are involved where Person is the super class and Student and Teacher are sub-classes with their own properties declared as instance variables. Now the question is how many tables are required and moreover how to link the tables so that Student gets three properties of id…

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