hibernate Interview Questions and Answers | DevGlan
In this tutorial of Many to one mapping in hibernate we will discuss about the Many To One Relationship Mapping. Actually Many To One is the reverse of the. Hibernate interview questions and answers for freshers and experienced - Object Relational How do you implement one to many relationships in Hibernate?. 6 days ago Hibernate Interview Questions: Hibernate is an Object-Relational Mapping (ORM ) solution What is a Many-to-One association in Hibernate?.
Long transactions might span several database transactions. Answer Lazy fetching decides whether to load child objects while loading the Parent Object. You need to do this setting respective hibernate mapping file of the parent class. Question 32 What is an SQL dialect?Java interview questions:- How can we implement Many To One relation in database using Hibernate?
The SQL dialect, derived from the Structured Query Language, uses human-readable expressions to define query statements. Question 33 What is in HQL? Question 34 What is the use of projection in hibernate? You can also use Projections to specify distinct clauses and aggregate functions like maxsum and so on.
Like modifying the select clause in an SQL query. Question 35 What is Lazyinitializationexception in hibernate? Answer Indicates access to unfetched data outside of a session context. For example, when an uninitialized proxy or collection is accessed after the session was closed.
Question 36 What are the different cascade types in hibernate? Question 38 What is hbm2ddl in hibernate? With create-drop, the database schema will be dropped when the SessionFactory is closed explicitly. Question 39 What is the use of dialect in hibernate? Question 40 Can I disable first level cache in hibernate? Answer The scope of cache objects is of session. Once session is closed, cached objects are gone forever.
Answer JDBC will always give better performance as compared to Hibernate for most of the database vendors. The choice of hibernate over jdbc and sql queries is not because of the performance but because of reasons mainly object persistence and database independence in terms of not writing database specific queries.
Question 43 What is the use of bag in hibernate? Answer Hibernate Bag is a java collection that stores elements without caring about the sequencing, but allow duplicate elements in the list.
A bag is a random grouping of the objects in the list. Question 44 What is the use of Mappedby in hibernate? Question 45 What is inverse true in hibernate? Answer The real meaning is that it defines which side is the parent or the relationship owner for the two entities parent or child. Question 46 What is a bidirectional relationship? In a bidirectional relationship, each entity has a relationship field or property that refers to the other entity.
- 30 Hibernate Interview Questions and Answers - Freshers, Experienced
- Hibernate Interview Questions
- hibernate Interview Questions and Answers
Question 47 What is the dirty checking in hibernate? Answer Hibernate allows dirty checking feature. All persistent objects are monitored by hibernate. Question 48 What are the important interfaces in hibernate? Question 50 What is difference between openSession and getCurrentSession? Answer If you set hibernate. If no row foundit return null. Question 52 What are different states of an entity bean in Hybernate?
Answer The Entity bean has three states: When ever we create a new object of Entity bean then we can say that is in Transient state,At that time any modification in the object state does not effect on database. When ever the Object of entity bean associated with session we can say that is in persistent state, if any change in the object statethen that modification effects in database. When ever the object is removed from session then it enters in to detached state.
Any modification on detached state objectdoes not effect in database.
Hibernate Interview Questions And Answers For Experienced
Question 53 Difference between hibernate session merge vs update? Answer Hibernate handles persisting any changes to objects in the session when the session is flushed. Merge should be used in that case. It merges the changes of the detached object with an object in the session, if it exists.
Question 54 Difference between save and saveorupdate in hibernate?
Answer The important difference between the org. Save method stores an object into the database. Question 55 What is the difference between save and persist in hibernate? Answer persist — Hibernate persist is similar to save with transaction and it adds the entity object to the persistent context, so any further changes are tracked.
If the object properties are changed before the transaction is committed or session is flushed, it will also be saved into database. Answer Hibernate collections types are: Question 57 How to implement Joins in Hibernate? Answer Using HQL we can implement joins in hibernate. For example, select e. In this query, Employee class should have a variable named address. Answer A named query is a SQL expression represented as a table.
In a named query, you can specify an SQL expression to select rows and columns returned from one or more tables in one or more data sources. Question 60 What are callback interfaces in hibernate?
Answer Callback interface for Hibernate code. The typical implementation will call Session. Answer In a non-managed environment, Hibernate is usually responsible for its own database connection pool. The application developer has to manually set transaction boundaries begin, commit, or rollback database transactions themselves.
Question 62 What are the mapping associations used in hibernate? Answer There are two mapping associations used in hibernate, they are: Question 64 What is hibernate criteria join? Answer Java Management Extensions JMX is a Java technology that supplies tools for managing and monitoring applications, system objects, devices such as printers and service-oriented networks.
Hibernate Interview Questions
Those resources are represented by objects called MBeans for Managed Bean. Question 68 What are the fetching strategies in hibernate? Answer There are four fetching strategies 1.
Question 69 What are derived properties in hibernate? Answer In Hibernate a derived property also called a calculated property is a read-only property whose value is calculated at fetch time using SQL expressions.
Question 70 What is version property in hibernate? No, Session object is not thread-safe in Hibernate and intended to be used with-in single thread in the application.
Hibernate SessionFactory getCurrentSession method returns the session bound to the context. But for this to work, we need to configure it in hibernate configuration file.
Once the session factory is closed, this session object gets closed. We should close this session object once we are done with all the database operations. We should open a new session for each request in multi-threaded environment. SessionFactory is both Immutable and thread-safe and it has just one single instance in Hibernate application. It is used to create Session object and it also provide caching by storing SQL queries stored by multiple session.
The second level cache is maintained at SessionFactory level. This can be a difficult and tricky question for less experienced Java developers who are not familiar with thread-safety and Immutability.
Defines the field which owns the relationship. This element is specified on the inverse non-owning side of the association. It is only needed when relationship is unidirectional. Owning side is the entity having foreign key column. Lazy initialization means you don't initialize entire object, it only initializes the first level variables member variablet initializes the list when we access it. Supose an user have list of addresses that he has visited and when we get details it only fetchesnthe first level variable but not the list.
Both are from session interfce and both will be used for retrieving object from DB.