Скачать или смотреть Hql Delete Query | Hibernate Query Language environmental setup | HQL Queries | HQL with Mysql

Title:
Hql Delete Query | Hibernate Query Language environmental setup | HQL Queries | HQL with Mysql

what is hibernate?
Hibernate is an Object-Relational Mapping(ORM) solution for JAVA and it raised as an open source persistent framework created by Gavin King in 2001. It is a powerful, high performance Object-Relational Persistence and Query service for any Java Application.
Hibernate maps Java classes to database tables and from Java data types to SQL data types and relieve the developer from 95% of common data persistence related programming tasks.
Hibernate sits between traditional Java objects and database server to handle all the work in persisting those objects based on the appropriate O/R mechanisms and patterns.

Advantages Of Hibernate:
• Hibernate takes care of mapping Java classes to database tables using XML files and without writing any line of code.
• Provides simple APIs for storing and retrieving Java objects directly to and from the database.
• If there is change in Database or in any table then the only need to change XML file properties.
• Abstract away the unfamiliar SQL types and provide us to work around familiar Java Objects.
• Hibernate does not require an application server to operate.
• Manipulates Complex associations of objects of your database.
• Minimize database access with smart fetching strategies.
• Provides Simple querying of data.

what is Hibernate Query Language?
Hibernate Query Lang uag e (HQL) is an object-oriented query lang uag e, similar to SQL, but instead of operating on tables and columns, HQL works with persistent objects and their properties. HQL queries are translated by Hibernate into conventional SQL queries which in turns perform action on database.

Althoug h you can use SQL statements directly with Hibernate using Native SQL but I would recommend to use HQL whenever possible to avoid database portability hassles, and to take advantag e of Hibernate's SQL generation and caching strategies.

Keywords like SELECT , FROM and WHERE etc. are not case sensitive but properties like table and column names are case sensitive in HQL.

Example:
String hql = "DELETE FROM Employee " +
"WHERE id = :employee_id";
Query query = session.createQuery(hql);
query.setParameter("employee_id", 10);
int result = query.executeUpdate();
System.out.println("Rows affected: " + result);

Demo Description:
The demo shows how to integrate hibernate and how to code with hibernate query language. The query will differ in case of HQl and in hibernate there will be no query.