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manual

SELECT clause (JPQL / Criteria API)

Explains how to use the SELECT clause and projections in a JPA/JPQL query.... managed entity objects is a major advantage of JPQL. For example, the following query returns Country objects that become managed by ... can also return results which are not entity objects. For example, the following query returns country names as String instances, ...

 
forum_thread

Best practice: Database update/migration of embedded databases in products

Hello Support, what experience do you have for data migration within a product? An example: There are three versions of a product (v1.0; v1.1, v2.0). In each version, the entities have been modified. Attributes added, removed and renamed. If attributes were removed, then only because the data is now held otherwise. ... you have for data migration within a product? An example: There are three versions of a product (v1.0; v1.1, v2.0). In ... The product store user data in the ObjectDB-Database. Example: V1.0: EntityPerson{ String firstName;  String familyName; ...

 
forum_thread

Schema update: package, class and field

Hello, how can it be specified in the schema, that an entity is moved to another package? Package Structure (version 1) com |- btc |- impl |- Class1.java |- internal |- Class2.java |- Class3.java Now I want to move Class2   from com.btc.internal to com.btc.impl ... doesn't works.   I had extended a example in which i already rename a field. Only rename the field  [example works] <package name = ...   Only move the (embeddable) class [example works too] <package name = ...

 
api-jpa

javax.persistence.IdClass

Specifies a composite primary key class that is mapped to multiple fields or properties of the entity.(Annotation of JPA)

 
api-jpa

javax.persistence.Embedded

Specifies a persistent field or property of an entity whose value is an instance of an embeddable class.(Annotation of JPA)

 
api-jpa

javax.persistence.OrderColumn

Specifies a column that is used to maintain the persistent order of a list.(Annotation of JPA)

 
api-jpa

javax.persistence.MapKeyEnumerated

Specifies the enum type for a map key whose basic type is an enumerated type.(Annotation of JPA)

 
api-jpa

javax.persistence.ElementCollection

Defines a collection of instances of a basic type or embeddable class.(Annotation of JPA)

 
api-jpa

javax.persistence.AttributeOverrides

Used to override mappings of multiple properties or fields.(Annotation of JPA)

 
api-jpa

javax.persistence.PrimaryKeyJoinColumns

Groups PrimaryKeyJoinColumn annotations.(Annotation of JPA)