# @ejbgen:automatic-key-generation Annotation

For a CMP entity bean, specifies how primary keys are auto-generated. Primary keys can be auto-generated using Oracle or SQL server specific methods or a vendor-neutral named sequence table. A summary of the syntax is provided below. For detailed explanations and examples, see the related topics at the bottom of the page.

## Scope

Class tag for a CMP entity bean.

## Syntax

@ejbgen:automatic-key-generation

type="keyGeneratorType"

[name="nameKeyGenerator"]

[cache-size="keyChacheSize"]

## Attributes

type

Required. The following key generator keywords are available:

> - Oracle. Use an Oracle SEQUENCE database table.
> - SQLServer. Use SQL Server's IDENTITY column.
> - SQLServer2000. Use SQL Server 2000's IDENTITY column.
> - NamedSequenceTable. Use a named sequence table.

> Note. The SQLServer2000 option is the same as SQLServer, except that SQLServer uses @@IDENTITY column to get the generated key value and SQLServer2000 uses the SCOPE_IDENTITY() function instead.

cache-size

Optional. Specifies the size of the key cache.

name

Optional. Specifies the name of the Oracle SEQUENCE table or the name of the named sequence table.

## Remarks

The following rules apply to this tag's use:

- When you specify the Oracle type, you must specify the name of the SEQUENCE table and the cache-size. The cache-size must match the value of the increment.

- When you specify the SQLServer(2000) type, you can optionally specify the cache-size. The cache-size determines how many keys are fetched from the named sequence table by the EJB container. A large cache size lowers the number of trips to the table.

- When you specify the NamedSequenceTable type, you must specify the name of the named sequence table and the cache-size. The cache-size determines how many keys are fetched from the named sequence table by the EJB container. A large cache size lowers the number of trips to the named sequence table.

Related Topics

Automatic Primary Key Generation

Automatic Primary Key Generation Sample