Question Answer Example Code
What is the purpose of the @Entity annotation in Hibernate? Marks a class as a Hibernate entity, mapping it to a database table. java @Entity public class Employee { @Id @GeneratedValue private int id; private String name; }
What is the purpose of the @Table annotation in Hibernate? Specifies the table name and schema. java @Entity @Table(name = "employees") public class Employee { @Id @GeneratedValue private int id; }
What is the difference between @Id and @GeneratedValue? @Id marks a field as the primary key, while @GeneratedValue defines how the key is generated. java @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private int id;
What is the purpose of @Column annotation? Defines column properties such as name, length, and uniqueness. java @Column(name = "emp_name", length = 50, unique = true) private String name;
What is the difference between @OneToOne and @OneToMany relationships? @OneToOne: One entity related to one entity. @OneToMany: One entity related to multiple entities. java @OneToOne private Address address; @OneToMany(mappedBy = "department") private List<Employee> employees;
What is the difference between @ManyToOne and @ManyToMany relationships? @ManyToOne: Multiple entities linked to a single entity. @ManyToMany: Many-to-many relationship between entities. java @ManyToOne private Department department; @ManyToMany private List<Course> courses;
What is the use of @JoinColumn in Hibernate? Defines the foreign key column in a relationship. java @OneToOne @JoinColumn(name = "address_id") private Address address;
What is optimistic and pessimistic locking in Hibernate? Optimistic Locking: Uses versioning (@Version) to prevent conflicts. Pessimistic Locking: Locks a record to prevent concurrent modifications. java @Version private int version;
What is the use of @Embedded and @Embeddable annotations? Enables embedding one class into another without creating a separate table. java @Embeddable public class Address { private String city; private String state; } @Entity public class Employee { @Embedded private Address address; }
What is a Named Query in Hibernate? A predefined query that can be reused. java @NamedQuery(name = "Employee.findAll", query = "FROM Employee") public class Employee { } Query query = session.getNamedQuery("Employee.findAll"); List<Employee> employees = query.list();
What is a Native SQL query in Hibernate? Executes raw SQL queries. java Query query = session.createSQLQuery("SELECT * FROM employees").addEntity(Employee.class); List<Employee> employees = query.list();
What are the different fetching strategies in Hibernate? Lazy Fetching: Loads data when needed. Eager Fetching: Loads related data immediately. java @OneToMany(fetch = FetchType.LAZY) @OneToMany(fetch = FetchType.EAGER)
What is Hibernate Interceptor? Allows custom logic before or after database operations. java class MyInterceptor extends EmptyInterceptor { @Override public void onDelete(Object entity, Serializable id, Object[] state, String[] propertyNames, Type[] types) { System.out.println("Entity deleted: " + entity); } } Session session = sessionFactory.withOptions().interceptor(new MyInterceptor()).openSession();
What is the difference between clear(), evict(), and close() in Hibernate? clear(): Removes all objects from session cache. evict(Object obj): Removes a specific object from cache. close(): Closes session completely. java session.evict(employee); session.clear(); session.close();
What is the difference between Hibernate and JPA? JPA is a specification for ORM, while Hibernate is an implementation of JPA with extra features. java @Entity public class Employee { }


Instance Of Java

We will help you in learning.Please leave your comments and suggestions in comment section. if you any doubts please use search box provided right side. Search there for answers thank you.
«
Next
Newer Post
»
Previous
Older Post

No comments

Leave a Reply

Select Menu