 24 | are useful in representing composite primary keys as explained in the Primary Key section of the ObjectDB manual. |
24 | 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 |
24 | . 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 |
23 | Explains settings and performance tuning of the ObjectDB Java object database for JPA/JDO. |
22 | get methods) Specifies a primary key column that is used as a foreign key to join to another table ... to a primary table; and it may be used in a OneToOne mapping in which the primary key ... to have the same names as the primary key columns of the primary table of the superclass. Example |
19 | ObjectDB 2.0 supports many new features and improvements, including: Most of the features of the new JPA 2.0 and JDO 2.2 APIs. User defined IDs (primary key) and sequences. Support of unlimited index keys size. SQL like queries ("select from ... where ..."). Real non blocking multithreading in |
19 | , however, do not have an identity (primary key) of their own which leads to some limitations (e.g ... and keys and values in maps) are either null values or instances of persistable types. In addition |
19 | Annotation Element javax.jdo.annotations.Key ForeignKeyAction deleteAction Delete action to apply to the foreign key for the key. Returns: delete action to apply to the foreign key for the key Default value: javax.jdo.annotations.ForeignKeyAction.UNSPECIFIED Since: JDO 2.1 |
19 | Annotation Element javax.jdo.annotations.Key ForeignKeyAction updateAction Update action to apply to the foreign key for the key. Returns: update action to apply to the foreign key for the key Default value: javax.jdo.annotations.ForeignKeyAction.UNSPECIFIED Since: JDO 2.1 |
19 | Method javax.jdo.Query void addExtension( String key, Object value ) Add a vendor-specific extension to this query. The key and value are not standard. An implementation must ignore keys that are not recognized. Parameters: key - the key of the extension value - the value of the extension Since: JDO 2.0 |