12/15/2023 0 Comments Hibernate query language![]() ![]() ![]() The SessionFactory is a thread safe object and used by all the threads of an application. These files are hibernate.properties and .Ĭlass Mapping Setup − This component creates the connection between the Java classes and database tables.Ĭonfiguration object is used to create a SessionFactory object which in turn configures Hibernate for the application using the supplied configuration file and allows for a Session object to be instantiated. The Configuration object provides two keys components −ĭatabase Connection − This is handled through one or more configuration files supported by Hibernate. It represents a configuration or properties file required by the Hibernate. It is usually created only once during application initialization. The Configuration object is the first Hibernate object you create in any Hibernate application. JNDI and JTA allow Hibernate to be integrated with J2EE application servers.įollowing section gives brief description of each of the class objects involved in Hibernate Application Architecture. JDBC provides a rudimentary level of abstraction of functionality common to relational databases, allowing almost any database with a JDBC driver to be supported by Hibernate. Hibernate uses various existing Java APIs, like JDBC, Java Transaction API(JTA), and Java Naming and Directory Interface (JNDI). Hibernate makes use of the database and configuration data to provide persistence services (and persistent objects) to the application.įollowing is a very high level view of the Hibernate Application Architecture.įollowing is a detailed view of the Hibernate Application Architecture with its important core classes. Note that, if the attribute to sort by is a primitive type like an int, a PresisitenceException will thrown.įor example, if the value of f.Hibernate has a layered architecture which helps the user to operate without having to know the underlying APIs. This_.NAME is null then 0 else 1 end, this_.NAME desc The corresponding SQL query follows – with the is null then 0 else 1 clause: Hibernate: select this_.ID as ID1_1_1_, this_.NAME as NAME2_1_1_, OrderBy.add((Foo.class,"name", SortDirection.ASCENDING, NullPrecedence.FIRST)) This_.NAME is null then 1 else 0 end, this_.NAME ascĪlternatively, we can also place the nulls at the beginning of a descending ordered list: CriteriaQuery selectQuery = session.getCriteriaBuilder().createQuery(Foo.class) ID1_0_0_, bar2_.NAME as NAME2_0_0_ from FOO order by case when Here is the underlying SQL query – with the is null then 1 else 0 clause: Hibernate: select this_.ID as ID1_1_1_, this_.NAME as NAME2_1_1_, OrderBy.add((Foo.class,"name", SortDirection.ASCENDING, NullPrecedence.LAST)) Query query = session.createQuery(selectQuery) Hibernate Criteria Object API makes it simple to change that default and place nulls at the end of an ascending ordered list: CriteriaQuery selectQuery = session.getCriteriaBuilder().createQuery(Foo.class) Sorting With Hibernate Criteriaīy default, when the attribute to sort by has null values, it is up to the RDMS to decide the precedence. The order of elements is as returned by the database, undefined.”Īs a side-note, it would be is possible to work around this limitation by using legacy XML configuration for Hibernate, and replacing the element with a element. ![]() One thing to keep in mind is that it is not possible to to sort Lists as was the case with JPA. NAME2_1_1_, foolist0_.BAR_ID as BAR_ID3_1_1_, foolist0_.idx as idx4_1_1_įrom FOO foolist0_ where foolist0_.BAR_ID=? order by foolist0_.NAME desc Order by bar0_.ID Hibernate: select foolist0_.BAR_ID as BAR_ID3_0_0_,įoolist0_.ID as ID1_1_0_, foolist0_.ID as ID1_1_1_, foolist0_.NAME as The resulting SQL statement shows that the sorted Foo’s are placed in a fooList: Hibernate: select bar0_.ID as ID1_0_, bar0_.NAME as NAME2_0_ from BAR bar0_ Query query = session.createQuery(hql, Bar.class) ![]()
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