http://www.oracle.com/technology/tech/java/oc4j/ejb3/howtos-ejb3/howtoejb30mappingannotations/doc/how-to-ejb30-mapping-annotations.html#id
@Id
annotation to specify an entity field as the primary key. In this example, primary key values are generated using a table generator (see 'Configuring JPA Entity Automatic Primary Key Generation').equals
and hashCode
methods.@EmbeddedId
annotation.empName
and birthDay
must correspond in name and type to properties in the entity class. Example 7-5 shows how to configure a JPA entity with this nonembedded composite primary key class using the @IdClass
annotation. Because entity class fields empName
and birthDay
are used in the primary key, you must also annotate them using the @Id
annotation.Type | Description | For more information, see .. |
---|---|---|
Generated Id Table | A database table that the container uses to store generated primary key values for entities. Typically shared by multiple entity types that use table-based primary key generation. Each entity type will typically use its own row in the table to generate the primary key values for that entity class. Primary key values are positive integers. | 'Table Sequencing' in the Oracle TopLink Developer's Guide |
Table Generator | A primary key generator, which you can reference by name, defined at one of the package, class, method, or field level. The level at which you define it will depend upon the desired visibility and sharing of the generator. No scoping or visibility rules are actually enforced. Oracle recommends that you define the generator at the level for which it will be used. This generator is based on a database table. | 'Table Sequencing' in the Oracle TopLink Developer's Guide |
Sequence Generator | A primary key generator which you can reference by name, defined at one of the package, class, method, or field level. The level, at which you define it, will depend upon the desired visibility and sharing of the generator. No scoping or visibility rules are actually enforced. Oracle recommends that you define the generator at the level for which it will be used. This generator is based on a sequence object that the database server provides. | Mount and blade warband key generator free download. 'Native Sequencing With an Oracle Database Platform' in the Oracle TopLink Developer's Guide 'Native Sequencing With a Non-Oracle Database Platform' in the Oracle TopLink Developer's Guide |
http://www.oracle.com/technology/tech/java/oc4j/ejb3/howtos-ejb3/howtoejb30mappingannotations/doc/how-to-ejb30-mapping-annotations.html#sequencing
@TableGenerator
annotation to specify a primary key value generator based on a database table. The TopLink JPA persistence provider will attempt to create this table at deployment time: if it cannot, then you must follow your database documentation to ensure that this table exists before deployment. When a new instance of Address
is created, a new value for entity field id
is obtained from ADDRESS_GENERATOR_TABLE
. In this case, you must set the @GeneratedValue
annotation attribute strategy
to TABLE
and generator
to ADDRESS_TABLE_GENERATOR
.@SequenceGenerator
annotation to specify a primary key value generator based on a sequence object provided by the database. The TopLink JPA persistence provider will attempt to create this object at deployment time: if it cannot, then you must follow your database documentation to ensure that this sequence object exists before deployment. When a new instance of Address
is created, a new value for entity field id
is obtained from database sequence object ADDRESS_SEQ
. In this case, you must set the @GeneratedValue
annotation attribute strategy
to SEQUENCE
and generator
to ADDRESS_SEQUENCE_GENERATOR
.@GeneratedValue
annotation to specify a primary key value generator based on a primary key identity column (autonumber column). When a new instance of Address
is persisted, the database assigns a value to the identity column. In this case, the TopLink JPA persistence provider re-reads the inserted row and updates the in-memory Address
entity to set id
to this value.