Defining EJB 3 Association Mappings

EJB 3 persistence provides support for most of the association mapping strategies. We will just address the differences here.

One association must be defined between two Entity classes or one Entity class and one Mapped superclass before it can be mapped. Association mapping with a Mapped superclass as the target will be ignored. Embeddable classes can be either the source or the target of associations.

Mapping for associations with association class is not currently supported. You must separate each kind of associations into two equivalent associations.

For more informations about mapping, see Object/Relational (O/R) Mapping.

• Mapping One-to-one Associations
  EJB 3 persistence supports both bi-directional one-to-one association mapping and unidirectional one-to-one association mapping.
• Mapping One-to-many Associations
  EJB 3 persistence supports bi-directional one-to-many association mapping, unidirectional one-to-one association mapping and unidirectional one-to-many association mapping.
• Mapping Many-to-many Associations
  EJB 3 persistence supports both bi-directional many-to-many association mapping and unidirectional many-to-many association mapping.
• Defining EJB 3 Association Mapping Options
  The following EJB 3-specific options for association mappings are available on the EJB 3 Persistence tab of an association's property sheet: