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Hibernate
n/a
36
Computer Science
Graduate
05/08/2013

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Term

 What does the DTD do?

Definition
It provides a set of rules for a XML file to follow.
Term

 What are the two types of XMLs? What is the difference?

Definition

Valid – follows a DTD.

Well-Formed – regular XML code, no DTD.

Term

 Where is a DTD located?

Definition
In a XML file.
Term

Define the Transient state of a Hibernate object.

Definition
An object is transient if it has just been instantiated using the new operator, and it is not associated with a Hibernate session.
Term

Define the Persistent state of a Hibernate object.

Definition
A persistent instance has a representation in the database and an identifier value.
Term

Define the Detached state of a Hibernate object.

Definition
A detached instance is an object that has been persistent, but its session has been closed.
Term

In Hibernate, what two methods make an object persistent? What is the difference?

Definition

persist() - makes a transient instance persistent.

save() - guarantee to return an identifier.

Term

What are the six features of Hibernate?

Definition

1. Has comprehensive API, support for CRUD operation.

2. No complex queries.

3. Caching support.

4. Criteria API support for retrieving data.

5. Has own Query language (HQL) & also supports native SQL.

6. Lazy loading/fetching.

Term

What is a proxy object?

Definition
A temporary object that holds data before it is obtained from the database.
Term

How do you query a database in Hibernate?

(Hint: 3)

Definition

- Hibernate's main methods.

- HQL.

- Criteria API.

Term

What is first-level caching?

Definition
It is caching that always associates with the Session object. Used by default, it processes one transaction after another.
Term

What is second-level caching?

Definition
It is caching that always associates with the Session Factory object. It loads the objects at the Session Factory level so the object will be available to the entire application.
Term

What is a foreign key?

Definition
A primary key of another table.
Term

What are the core interfaces of Hibernate?

 (Hint: 6)

Definition

SessionFactory, Session, Configuration, Criteria, Query, Transaction.

Term

What are the four relationships between tables?

Definition
One to One, One to Many, Many to One, Many to Many.
Term

What is an Association?

Definition
A relationship between tables.
Term

What are the two types of Associations?

Definition
Aggregation and Composition
Term
Define the Association type Aggregation.
Definition

A weak form of association, it is where a child table can still exist even if the parent table is deleted.

 

Term
Define the Association type Composition
Definition
It is a strong type of association, it is where a child table is completely dependant on a parent table. If the parent table deletes all, the child table will be deleted.
Term
How does a application obtain a Session interface?
Definition
Session session = SessionFactory.openSession();
Term
When is the Hibernate proxy used?
Definition
When calling session.load().
Term
Give an example of a HQl.
Definition
"from Person as person"
Term
What is lazy loading?
Definition
When loading the parent entity, the child entity will only be loaded when you request it.
Term

What are some minor level annotations?

(Hint: 4)

Definition
@Temporal, @JoinColumn, @SequenceGenerator, @Cache.
Term

How do you enable second level caching?

(Hint: 2)

Definition

- In hibernate.cfg.xml, inform it that you are using 2nd level caching and specify why provider you are using.

- In hbm.xml, configure entities and collections to be cached.

Term
What does a instance of the Configuration interface do?
Definition
It allows the application to specify properties and mapping documents to be used when creating a SessionFactory.
Term
What is the Query interface?
Definition
It is an object-oriented representation of a Hibernate query.
Term
What does the Transaction interface do?
Definition

It allows the application to define units of work, while maintaining abstraction from the transaction implementation.

If one step fails, the whole transaction fails.

Term
What does caching do?
Definition
It stores data already loaded from the database, so that traffic between the application and the database will be reduced.
Term

Where are named SQL Queries found?

Definition

Named SQL queries are defined in the mapping xml document and called whenever required.

Term
What is cascade?
Definition
After an operation (save, update, delete) is performed on an entity, it specifics what operations to perform on relational entities.
Term
What is inverse?
Definition
Indicates which end of a relationship should be ignored.
Term
When do you use merge()?
Definition
It should be used if you want to save your modifications at any time without knowing the state of a session.
Term
When do you use update()?
Definition
It should be used to save the data when the session does not contain an already persistent instance with the same identifier.
Term
How does a sorting collection work?
Definition

It sorts a collection by utilizing the sorting features provided by the Java collections framework.

Term
How does a order collection work?
Definition
By sorting a collection by specifying the order-by clause when retrieved.
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