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Criteria Query Selection and Results

The JPA Criteria API interfaces in this group are in use for setting the SELECT and ORDER BY ... clause in a criteria query is represented by Selection: Because Selection is a super interface ... expressions can be represented by CompoundSelection, which is itself a subinterface of Selection
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2

JPA Lifecycle Events

and are invoked automatically by JPA when these events occur. Internal Callback Methods Internal callback ... - when an entity is identified as modified by the EntityManager. @PostUpdate - after updating an entity in ... events by marking it with more than one annotation. By default, a callback method in a super entity
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2

CRUD Database Operations with JPA

a managed entity) by the persist method. The new Point objects are physically stored in the database ... objects in the database by using a simple query: Query q1 = em.createQuery("SELECT COUNT(p) FROM Point ... (using an ORDER BY clause) and even group results (using GROUP BY and HAVING clauses). JPQL
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2

SELECT clause (JPQL / Criteria API)

, the following query returns Country objects that become managed by the EntityManager em: TypedQuery ... can be added to the SELECT clause by using a bound JOIN variable in the FROM clause. Nested path expressions ... with the containing entities. Therefore, embedded objects that are retrieved directly by a result path expression
JPA Doc
2

JPA Queries

Queries are represented in JPA by the Query and TypedQuery interfaces: The JPA Query API section ... only at runtime (e.g. depending on which fields are filled by a user in a form) can be done by ... a cleaner alternative that enables building a dynamic query by using instances of special types
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2

evictAll() behavior

(L1) cache. But evictAll does not affect objects that have been changed by the current PersistenceManager - it is useful only to see changes that have been committed by other persistence managers ... does not affect objects that have been changed by the current PersistenceManager" Cool, that is exactly
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2

Performance with large databases

access. Retrieval by an indexed field is usually composed of two steps: First finding the ID and then retrieval by ID. sjzlondon ... to take the most time are those that retrieve data from the store. This may be explained by examining the ratio between ... and the ObjectDB cache size). Except this, ObjectDB performance should not be affected significantly by
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2

DELETE Queries in JPA/JPQL

As explained in chapter 2, entity objects can be deleted from the database by: Retrieving ... transaction, either explicitly by calling the remove method or implicitly by a cascading operation. Applying changes to the database by calling the commit method. JPQL DELETE queries provide
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2

JPA Criteria API Queries

, are defined by instantiation of Java objects that represent query elements. A major advantage of using ... factory of criteria queries and criteria query elements. It can be obtained either by the EntityManagerFactory's getCriteriaBuilder method or by the EntityManager's getCriteriaBuilder method
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2

Literals in JPQL and Criteria Queries

, 077L), a feature that is not currently supported by all JPA implementations. String Literals JPQL ... . 'Adam', '') and a single quote character in a string is represented by two single quotes (e.g ... ", "abcd\n1234") but this is not supported by all the JPA implementations. Unlike most other JPQL