Introduction To Hibernate Query Language (HQL)

In this tutorial you will learn about Hibernate Query Language.

Introduction To Hibernate Query Language (HQL)

Introduction To Hibernate Query Language (HQL)

In this tutorial you will learn about Hibernate Query Language.

HQL is an abbreviation of Hibernate Query Language. It is a powerful query language, inspired by SQL that the Hibernate uses. When looking a HQL it is as similar to SQL but the HQL is different from SQL, HQL is fully object-oriented and it supports inheritance, polymorphism, abstraction. Queries in HQL are case-insensitive excluding the name of classes of java and the properties. for example in query WHerE is as same to whERe but a class name roseindia.net.HibernateExample is not same as roseindia.net.Hibernateexample.

Benefits of Hibernate Query Language is :

  1. Learning (HQL) Query in Hibernate is easy.
  2. HQL uses the (.) extension as it is used in object-orientation.
  3. Different SQL databases can be accessed by a single language provided by the HQL with a little different kind of SQL.
  4. HQL supports for relational operations. Using HQL a SQL query is allowed to be represented as an object form because in HQL rather tables and columns Classes and properties are used.
  5. HQL returns result as Object, this feature of HQL reduces the process of creation of an object and population of data from ResultSet.
  6. HQL provides database independent query writing.

Example :

In this example I will write a SQL query and a corresponding HQL query which will demonstrate you how a HQL is looking as same as SQL and how both are different. Let's suppose there is a table 'person' with their fields 'Id', 'Name', 'PersonType' having some value.

1. Writing a query in SQL 

SELECT name FROM person WHERE id = "4"

2. A corresponding HQL query can be written as :

SELECT per.name FROM person per WHERE per.id = "4"

Some of the common HQL queries statements / clause are :

  • select
  • from
  • where
  • group by
  • order by
  • insert
  • update
  • delete

Each of the above statements / clause is explained individually. In the next section of this tutorial.

Tutorials

  1. Introduction To Hibernate 4.0
  2. Complete Hibernate 4.0 Tutorial
  3. Hibernate 4 Tutorial
  4. What's New In Hibernate 4.0 release
  5. Hibernate Architecture
  6. Download Hibernate 4
  7. Hibernate create POJO classes
  8. Hibernate Configuration File
  9. First Hibernate Application
  10. First Hibernate 4 Example with Eclipse
  11. Hibernate 4 Supported Databases List
  12. Hibernate generator Element
  13. Hibernate 4 Annotations
  14. Hibernate 4 Annotation Example
  15. Hibernate 4 One to One Mapping using Annotation
  16. Hibernate 4 One to Many mapping using Annotation
  17. Hibernate One to One Mapping using XML
  18. Hibernate 4 One to Many mapping using XML
  19. Hibernate 4 Many to Many Mapping using Annotation
  20. Hibernate 4 Many to Many Mapping using Xml
  21. Hibernate update Method
  22. Hibernate persist Method
  23. Hibernate saveOrUpdate Method
  24. Hibernate SELECT Clause
  25. Hibernate FROM Clause
  26. Hibernate One to Many Bi-directional Mapping
  27. Hibernate WHERE Clause
  28. Hibernate ORDER BY Clause
  29. Introduction To Hibernate Query Language (HQL)
  30. Hibernate One to One Bi-directional Mapping
  31. Hibernate One to Many Indexed Mapping
  32. Hibernate One to many XML Mapping bag example
  33. Hibernate One to Many XML Mapping list Example
  34. Hibernate One to many XML mapping array Example
  35. Hibernate One to Many Self Join using Annotations
  36. Hibernate GROUP BY Clause
  37. Hibernate Many to Many Self Join using Annotations
  38. Hibernate update Query
  39. Hibernate delete Query
  40. Hibernate insert Query