About EJB Attribute Mappings

This topic covers how JDeveloper maps database tables to entity beans. For information on how database tables map to ADF business components, see About ADF Business Component Attribute Mappings.

How is the mapping between entity bean and table defined?

Entity beans map to database tables based on a predetermined map. For each column in the table, an attribute is created on the entity bean. So if you created a dept bean from DEPARTMENTS, the dept bean would have one attribute for every column in the database. The mapping mechanism is not exposed, nor can you change typemaps, but you can modify attributes and relationships using the Mapping Editor and EJB Editor.

How are entity bean constraints mapped to schema constraints?

Constraints are not mapped or preserved in either direction.

If foreign keys are detected in the tables, they will be engineered as CMR relationships. The UNIQUE and NOT NULL constraint determine the cardinality and composition of the relationship.

What isn't mapped?

You cannot map multiple tables to a single entity bean.
Constraints and validation rules embodied in the schema are not preserved when you engineer entity beans from tables. They are also not preserved if you generate tables from entity beans.
OC4J CMP mapping does not support mapping of Oracle Object Types.