javax.persistence.JoinColumn Maven / Gradle / Ivy
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package javax.persistence;
import java.lang.annotation.Target;
import java.lang.annotation.Retention;
import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
/**
* Is used to specify a mapped column for joining an entity association.
*
*
* Example:
*
* @ManyToOne
* @JoinColumn(name="ADDR_ID")
* public Address getAddress() { return address; }
*
*
* @since Java Persistence 1.0
*/
@Target({METHOD, FIELD})
@Retention(RUNTIME)
public @interface JoinColumn {
/**
* (Optional) The name of the foreign key column.
* The table in which it is found depends upon the
* context. If the join is for a OneToOne or Many-
* ToOne mapping, the foreign key column is in the
* table of the source entity. If the join is for a
* ManyToMany, the foreign key is in a join table.
*
* Default (only applies if a single join column is used):
* The concatenation of the following: the name of the
* referencing relationship property or field of the referencing
* entity; "_"; the name of the referenced primary key column.
* If there is no such referencing relationship property or
* field in the entity, the join column name is formed as the
* concatenation of the following: the name of the entity; "_";
* the name of the referenced primary key column.
*/
String name() default "";
/**
* (Optional) The name of the column referenced
* by this foreign key column. When used with
* relationship mappings, the referenced column is
* in the table of the target entity. When used inside
* a JoinTable annotation, the referenced key column
* is in the entity table of the owning entity, or
* inverse entity if the join is part of the inverse join
* definition.
*
* Default (only applies if single join column is being
* used): The same name as the primary key column of the
* referenced table.
*/
String referencedColumnName() default "";
/**
* (Optional) Whether the property is a unique key.
* This is a shortcut for the UniqueConstraint annotation
* at the table level and is useful for when the
* unique key constraint is only a single field. It is
* not necessary to explicitly specify this for a join
* column that corresponds to a primary key that is
* part of a foreign key.
*/
boolean unique() default false;
/** (Optional) Whether the foreign key column is nullable. */
boolean nullable() default true;
/**
* (Optional) Whether the column is included in
* SQL INSERT statements generated by the persistence
* provider.
*/
boolean insertable() default true;
/**
* (Optional) Whether the column is included in
* SQL UPDATE statements generated by the persistence
* provider.
*/
boolean updatable() default true;
/**
* (Optional) The SQL fragment that is used when
* generating the DDL for the column.
* Defaults to the generated SQL for the column.
*/
String columnDefinition() default "";
/**
* (Optional) The name of the table that contains
* the column. If a table is not specified, the column
* is assumed to be in the primary table of the
* applicable entity.
*/
String table() default "";
}