Sun Java System Application Server Enterprise Edition 8.1 2005Q2 Developer's Guide

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### Automatic Primary Key Generation

The Application Server supports automatic primary key generation for EJB 1.1, 2.0, and 2.1 CMP beans. To specify automatic primary key generation, give the `prim-key-class` element in the `ejb-jar-xml` file the value `java.lang.Object`. CMP beans with automatically generated primary keys can participate in relationships with other CMP beans. The Application Server does not support database-generated primary key values.

If the database schema is created during deployment, the Application Server creates the schema with the primary key column, then generates unique values for the primary key column at runtime.

If the database schema is not created during deployment, the primary key column in the mapped table must be of type `NUMERIC` with a precision of 19 or more, and must not be mapped to any CMP field. The Application Server generates unique values for the primary key column at runtime.

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