How execute criteria query in JPA?

Let’s see it step by step:

  1. Create an instance of Session from the SessionFactory object.
  2. Create an instance of CriteriaBuilder by calling the getCriteriaBuilder() method.
  3. Create an instance of CriteriaQuery by calling the CriteriaBuilder createQuery() method.

How get JPQL SQL string from Criteria query in JPA?

Getting the JPQL/SQL String Representations for a Criteria Query

  1. EclipseLink. EclipseLink’s Query representation is the org. eclipse. persistence. jpa.
  2. Hibernate. Hibernate’s Query representation is org. hibernate. Query.
  3. OpenJPA. OpenJPA’s Query representation is org. apache. openjpa.

What is CriteriaBuilder in Java?

public interface CriteriaBuilder. Used to construct criteria queries, compound selections, expressions, predicates, orderings. Note that Predicate is used instead of Expression in this API in order to work around the fact that Java generics are not compatible with varags. Since: Java Persistence 2.0.

What is expression in JPA?

Query expressions are the foundations on which JPQL and criteria queries are built. Every query consists of clauses – SELECT, FROM, WHERE, GROUP BY, HAVING and ORDER BY, and each clause consists of JPQL / Criteria query expressions.

What are the steps in creating a criteria query?

This query demonstrates the basic steps to create a Criteria query:

  1. Use an EntityManager instance to create a CriteriaBuilder object.
  2. Create a query object by creating an instance of the CriteriaQuery interface.
  3. Set the query root by calling the from method on the CriteriaQuery object.

What is Criteria query in hibernate?

The Hibernate Criteria Query Language (HCQL) is used to fetch the records based on the specific criteria. The Criteria interface provides methods to apply criteria such as retreiving all the records of table whose salary is greater than 50000 etc.

What is metamodel in JPA?

The JPA Metamodel API provides the ability to examine the persistent object model and retrieve details on managed classes and persistent fields and properties, similarly to the ability that Java reflection provides for general Java types.