Read Session session = sessionFactory.openSession() Įmployee employee = session.get(Employee.class, 1L) Transaction transaction = session.beginTransaction() Here are some examples:Ĭreate Session session = sessionFactory.openSession() To perform CRUD operations using Hibernate, you can use the Session object provided by Hibernate. The annotation is used to specify the join table, and the mappedBy attribute is used on the Course entity to specify the owning side of the relationship. A student can enroll in multiple courses, and a course can have multiple students, so a many-to-many relationship is established between them using the annotation on both entities. Public class Course = GenerationType.IDENTITY)Įxample of implementing a many-to-many relationship between Student and Course entities in Hibernate. Public class Student = GenerationType.IDENTITY) You will also need to specify a join table using the annotation. To implement a many-to-many relationship in Hibernate, you can use the annotation on both entities involved in the relationship. The annotation is used on the Employee entity to specify the foreign key column. A department can have multiple employees, so a one-to-many relationship is established between them using the annotation on the Department entity and the annotation on the Employee entity. = "departments")Įxample of implementing a one-to-many relationship between Department and Employee entities in Hibernate. The annotation can be used on the child entity to specify the foreign key column. To implement a one-to-many relationship in Hibernate, you can use the annotation on the parent entity to specify the mapping. Private String = "department", fetch = FetchType.LAZY)Įxample of using lazy loading in Hibernate to load the employees associated with a Department entity only when they are actually needed. Lazy loading can improve performance by reducing the amount of data that needs to be retrieved from the database, but it can also result in additional database queries if the associated entities are accessed later. In Hibernate, eager loading fetches all associated entities immediately when the parent entity is loaded from the database, while lazy loading loads the associated entities only when they are actually needed.Įager loading can result in more efficient querying of the database, as all necessary data is retrieved in a single query, but it can also cause performance issues and waste resources if unnecessary data is retrieved. Public class Department = GenerationType.IDENTITY)Įxample of using mapping annotations in Hibernate to specify the primary key, column names, and relationships between Employee and Department entities. Public class Employee = GenerationType.IDENTITY) Specifies a one-to-one or many-to-many relationship between two = "employees").Specifies a many-to-one or one-to-many relationship between two entities.Specifies the mapping between a Java class attribute and a database column.Specifies the strategy for generating unique primary keys.Specifies the primary key of an entity.In Hibernate, the common mapping types are: Įxample of a Hibernate configuration file that specifies the database connection information and mapping for the Employee class. The configuration file can include information about the database connection, mapping files or annotations, and other settings. You also need to create a SessionFactory object, which is used to create Session objects to interact with the database. To configure Hibernate with your application, you need to define a configuration file or use annotations to map Java classes to database tables.
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