Term
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Definition
| ORM is the automated persistence of objects in a Java application to the tables in a relational database. |
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Term
What does ORM consists of?
(Hint: 4) |
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Definition
a. API for performing basic CRUD operations.
b. API to express queries referring to classes.
c. Facilities to specify metadata.
d. Optimization facilities: dirty checking, lazy associations, fetching. |
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Term
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Definition
| Hibernate is a pure Java object-relational mapping (ORM) and persistence framework that allows you to map Java objects (POJO) to relational database tables using (XML) configuration files. |
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Term
Why do you need ORM tools like hibernate? |
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Definition
It shields developers from messy SQL by improving productivity, performance, maintainability, and portability. |
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Term
What does Hibernate simplify?
(Hint: 5) |
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Definition
- Saves and retrieves domain objects.
- Makes database columns and table name changes.
- Centralizes pre-save and post-retrieve logic.
- Complex joins for retrieving related items.
- Schema creation from object model. |
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Term
What is the need for the Hibernate xml mapping file? |
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Definition
| It tells Hibernate which tables and columns to use to load and store objects. |
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Term
What are the important tags of hibernate.cfg.xml?
(Hint: 4) |
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Definition
<hibernate-configuration>, <session-factory>, <property>, <mapping resource>
hibernate-configuration, session-factory, property, mapping resource |
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Term
What role does the Session interface play in Hibernate? |
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Definition
It is to create a single-threaded object that represents a conversation between the application and the persistent storage. |
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Term
What role does the SessionFactory interface play in Hibernate? |
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Definition
| The SessionFactory caches generates SQL statements (and other mapping metadata) that Hibernate uses at runtime. |
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Term
What is the general flow of Hibernate communication with RDBMS?
(Hint: 5) |
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Definition
- Load the hibernate.cfg.xml file and a create configuration object.
- Create session factory from configuration object.
- Get one session from this sessionFactory.
- Create HQL query.
- Execute query to get list containing Java objects. |
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Term
What is Hibernate Query Language (HQL)? |
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Definition
| A Hibernate specific query language that embodies a powerful and flexible way to query, store, update, and retrieve objects from a database. |
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Term
How do you map Java objects with Database tables with Hibernate-Mapping?
(Hint: 2) |
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Definition
- First you need to write Java domain objects (beans with setters and getters).
- Write hbm.xml, where we map java class to table and database columns to Java class variables. |
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Term
What's the difference between load() and get()? |
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Definition
- Load() is only good if the object exists, and will throw an exception if it doesn't. It also returns a proxy by default, and the database won't be hit until the proxy is invoked.
- Get() will return null if the object doesn't exists, and will hit the database immediately.
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Term
How do you define a sequence generated primary key in hibernate? |
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Definition
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Term
How do you invoke Stored Procedures in Hibernate? |
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Definition
| Stored procedures are defined in the mapping xml document and called whenever required. |
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Term
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Definition
| A simplified API for retrieving entities by composing Criterion objects. |
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Term
How do you switch between different relational databases in Hibernate?
(Hint: 3) |
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Definition
- In hibernate.cfg.xml change the driver properties (URL, username, and password).
-In hibernate.cfg.xml change the property tag (dialect).
- Use appropriate connector jar.
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Term
If you want to see the Hibernate generated SQL statements on console, what should you do? |
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Definition
In hibernate configuration file set as follows:
<property name=”show_sql”>true</property> |
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Term
What are some advantages of Hibernate over JDBC?
(Hint: 7) |
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Definition
With Hibernate....
1. ORM takes care of the mapping to database tables.
2. Provides transparent persistence while interacting with the RDBMS.
3. Provides a powerful query language.
4. Handles mapping of table data to application objects by itself.
5. Maintains object-table mapping.
6. The cache is set to application work space.
7. Enables developers to define a version type field. |
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Term
What are the Collection types in Hibernate?
(Hint: 5) |
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Definition
| Bag, Set, List, Array, Map. |
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Term
What do you mean by fetching strategy in Hibernate? |
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Definition
| It is a strategy Hibernate uses for retrieving associated objects if the application needs to navigate the association. |
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Term
What are Callback interfaces? |
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Definition
| A interfaces that allows a application to receive a notification when something interesting happens to an object (like loaded, saved, deleted). |
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Term
What are the types of Hibernate instance states?
(Hint: 3) |
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Definition
Transient – not associated with any data. After instantiation.
Persistent – associated with data. After CRUD method (save, update, delete).
Detached – no longer associated with the data. After session is closed.
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Term
What are the types of inheritance models in Hibernate?
(Hint: 3) |
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Definition
| Table per class hierarchy, Table per subclass, Table per concrete class. |
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Term
Spell out each role of of the Session Interface in Hibernate.
(Hint: 3) |
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Definition
- Wrap a JDBC connection.
- Factory to Transaction
- Holds a mandatory (first-level) cache of persistent objects.
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Term
| What can you use the Hibernate interfaces for? |
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Definition
| Storing and retrieving persistent objects and controlling transactions. |
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Term
What are some major Annotations in Hibernate?
(Hint: 4) |
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Definition
| @Entity, @Table, @Id, @GeneratedValue |
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