SequenceGenerator (Java EE 5 SDK)

javax.persistence Annotation Type SequenceGenerator

@Target(value={TYPE,METHOD,FIELD})
@Retention(value=RUNTIME)
public @interface SequenceGenerator

This annotation defines a primary key generator that may be referenced by name when a generator element is specified for the GeneratedValue annotation. A sequence generator may be specified on the entity class or on the primary key field or property. The scope of the generator name is global to the persistence unit (across all generator types).

   Example:

   @SequenceGenerator(name="EMP_SEQ", allocationSize=25)
 

从以下版本开始:

Java Persistence 1.0

name

public abstract String name

(Required) A unique generator name that can be referenced by one or more classes to be the generator for primary key values.

sequenceName

public abstract String sequenceName

(Optional) The name of the database sequence object from which to obtain primary key values.

Defaults to a provider-chosen value.

默认值:

""

initialValue

public abstract int initialValue

(Optional) The value from which the sequence object is to start generating.

默认值:

1

allocationSize

public abstract int allocationSize

(Optional) The amount to increment by when allocating sequence numbers from the sequence.

默认值:

50

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