About primary key

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Forum
24

Uninitialized primary key (id = 0)

Exception in thread "main" [ObjectDB 2.2.9_04] javax.persistence.RollbackException Failed to commit transaction: Attempt to reuse an existing primary key value (image.Meta:0) (error 613) at com.objectdb.jpa.EMImpl.commit(EMImpl.java:277) I check the db by explorer.jar, and find
Forum
23

Internal ObjectDB error by read the primary key

Internal ObjectDB error by read the primary key
FAQ
21

Is ObjectDB better than competing object databases?

databases do not support user defined primary keys, even though this is very useful in almost every application. ObjectDB supports user defined primary keys including composite primary keys. The support
Manual
21

Database Explorer [2011-09-21]

and primary key separated by # (e.g. Point#1). A collection can be specified as a comma separated list ... , which has to be specified by type and primary key separated by # (e.g. Point#1). The Edit > Set Reference ... type and primary key separated by # (e.g. Point#1). The Edit > Add to Collection > Add New Object
Manual
21

Database Explorer

and primary key separated by # (e.g. Point#1). A collection can be specified as a comma separated list ... , which has to be specified by type and primary key separated by # (e.g. Point#1). The Edit > Set Reference ... type and primary key separated by # (e.g. Point#1). The Edit > Add to Collection > Add New Object
JDO Doc
19

javax.jdo.annotations.Key

javax.jdo.annotations Annotation Key Target: Fields (including property get methods) Annotation for the key of a map relation. Corresponds to the xml element "key". Since: JDO 2.1 String column Name of the column to store the key in. Name of the column to store the key in. Returns: name
JPA Doc
18

javax.persistence.EntityManager

(Class entityClass, Object primaryKey) Find by primary key. Find by primary key. Search for an entity of the specified class and primary key. If the entity instance is contained in the persistence context, it is returned from there. Parameters: entityClass - entity class primaryKey - primary key
Manual
17

ORDER BY clause (JPQL / Criteria API)

. The following query returns Country objects ordered by currency as the primary sort key and by name as the secondary sort key: SELECT c.currency, c.name FROM Country c ORDER BY c.currency, c.name ... this case, the first expression is the primary order expression. Any additional order expression
JPA Doc
17

JPA Annotations for Classes

are useful in representing composite primary keys as explained in the Primary Key section of the ObjectDB manual.
JPA Doc
17

JPA Annotations for Value Generation

Automatically generated values are mainly useful for primary key fields, but are supported by ObjectDB also for regular (non primary key) persistent fields. At the field level, the @GeneratedValue with an optional GenerationType strategy is specified: The @GeneratedValue annotation