Maps a to-one cardinality association taking values over several entity types which arenot related by the usual entity inheritance, using a discriminator value stored on thereferring side of the relationship.

This is quite different todiscriminated inheritance where the discriminator is stored along with the referenced entity hierarchy.

For example, consider anOrder entity containingPayment information, where aPayment might be aCashPayment or aCreditCardPayment. An@Any mapping would store the discriminator value identifying the concrete type ofPayment along with the state of the associatedOrder, instead of storing it with thePayment entity itself.

 interface Payment { ... } @Entity class CashPayment { ... } @Entity class CreditCardPayment { ... } @Entity class Order {     ...     @Any     @AnyKeyJavaClass(UUID.class)   //the foreign key type     @JoinColumn(name="payment_id") //the foreign key column     @Column(name="payment_type")   //the discriminator column     @AnyDiscriminatorValue(discriminator="CASH", entity=CashPayment.class)     @AnyDiscriminatorValue(discriminator="CREDIT", entity=CreditCardPayment.class)     Payment payment;     ... }

In this example,Payment isnot be declared as an entity type, and is not annotated@Entity. It might even be an interface, or at most just amapped superclass, ofCashPayment andCreditCardPayment. So in terms of the object/relational mappings,CashPayment andCreditCardPayment wouldnot be considered to participate in the same entity inheritance hierarchy. On the other hand,CashPayment andCreditCardPayment must have the same identifier type.

It's reasonable to think of the "foreign key" in anAny mapping is really a composite value made up of the foreign key and discriminator taken together. Note, however, that this composite foreign key is only conceptual and cannot be declared as a physical constraint on the relational database table.

• AnyDiscriminator,JdbcType, orJdbcTypeCode specifies the type of the discriminator.
• AnyDiscriminatorValue specifies how discriminator values map to entity types.
• Column orFormula specifies the column or formula in which the discriminator value is stored.
• AnyKeyJavaType,AnyKeyJavaClass,AnyKeyJdbcType, orAnyKeyJdbcTypeCode specifies the type of the foreign key.
• JoinColumn specifies the foreign key column.

Of course,Any mappings are disfavored, except in extremely special cases, since it's much more difficult to enforce referential integrity at the database level.