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42

SELECT clause (JPQL / Criteria API)

, the following query returns country names as String instances, rather than Country objects: SELECT c.name FROM Country AS c Using path expressions, such as c.name, in query results is referred to as ... > query = em.createQuery( "SELECT c.name FROM Country AS c", String.class); List<String
40

JPA Queries

Queries are represented in JPA by the Query and TypedQuery interfaces: The JPA Query API section ... these interfaces to build and run JPQL queries. The TypedQuery interface (or alternatively the older Query interface) is the only neccessary interface for defining and running string based JPQL queries (e.g
40

DELETE Queries in JPA/JPQL

. Applying changes to the database by calling the commit method. JPQL DELETE queries provide an alternative way for deleting entity objects. Unlike SELECT queries, which are used to retrieve data from the database, DELETE queries do not retrieve data from the database, but when executed, delete specified
37

FROM clause (JPQL / Criteria API)

, and the same query can also be written as follows: SELECT c FROM Country c By default, the name of an entity class in a JPQL query is the unqualified name of the class (e.g. just Country with no package ... name annotation element. Multiple range variables are allowed. For example, the following query
37

JPA Query Expressions (JPQL / Criteria)

Query expressions are the foundations on which JPQL and criteria queries are built. Every query ... of JPQL / Criteria query expressions. Atomic Expressions The atomic query expressions are: JPQL / Criteria Variables JPQL / Criteria Parameters JPQL / Criteria Literals Every query expression consists
37

Criteria Query Selection and Results

and for representing query results as tuples. SELECT Clause Elements The content of the SELECT clause in a criteria query is represented by Selection: Because Selection is a super interface ... : See the SELECT in Criteria Queries section for more details and examples. ORDER BY Clause Elements Elements in
37

Criteria Query From Elements

The interfaces in this group are in use for setting a criteria query FROM clause. Criteria Query Variables The FROM clause in JPA queries (as in SQL) defines the query variables. Query variables are represented in criteria queries by descendant interfaces of the From interface: Range variables
36

Date and Time in JPQL and Criteria Queries

Date and time expressions may appear in JPQL queries: as date and time literals - e.g. {d '2011-12 ... that are evaluated to the date and time on the database server when the query is executed: CURRENT_DATE ... in Criteria Queries The CriteriaBuilder interface provides three factory methods for building date
36

javax.persistence.Query

name. This method is not required to be supported for native queries. Parameters: name - parameter ... name does not exist IllegalStateException - if invoked on a native query when the implementation does ... to be supported for criteria queries only. Parameters: name - parameter name type - type Returns: parameter
3

javax.jdo.Query

There are two namespaces in queries. Type names have their own namespace that is separate from the namespace for fields ... conflict with parameter names. The result of the query by default is a list of result class instances ... variableDeclaration - the name of the variable in the outer query to bind the results of the subquery

Getting Started

ObjectDB is very easy to use. Follow the Getting Started Tutorial and the Quick Tour manual chapter and in minutes you may be able to write and run first Java programs against ObjectDB.

Prior knowledge or experience in database programming (SQL, JDBC, ORM, JPA, etc.) is not required, but some background in using the Java language is essential.

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