@Repeatable(value=JoinColumns.class) @Target(value={METHOD,FIELD}) @Retention(value=RUNTIME) public @interface JoinColumn
JoinColumn annotation itself is
 defaulted, a single join column is assumed and the default values
 apply.
 
   Example:
   @ManyToOne
   @JoinColumn(name="ADDR_ID")
   public Address getAddress() { return address; }
   Example: unidirectional one-to-many association using a foreign key mapping
 
   // In Customer class
   @OneToMany
   @JoinColumn(name="CUST_ID") // join column is in table for Order
   public Set<Order> getOrders() {return orders;}
 ManyToOne, 
OneToMany, 
OneToOne, 
JoinTable, 
CollectionTable, 
ForeignKey| Modifier and Type | Optional Element and Description | 
|---|---|
| String | columnDefinition(Optional) The SQL fragment that is used when
 generating the DDL for the column. | 
| ForeignKey | foreignKey(Optional) Used to specify or control the generation of a
  foreign key constraint when table generation is in effect. | 
| boolean | insertable(Optional) Whether the column is included in
 SQL INSERT statements generated by the persistence
 provider. | 
| String | name(Optional) The name of the foreign key column. | 
| boolean | nullable(Optional) Whether the foreign key column is nullable. | 
| String | referencedColumnName(Optional) The name of the column referenced by this foreign
 key column. | 
| String | table(Optional) The name of the table that contains
 the column. | 
| boolean | unique(Optional) Whether the property is a unique key. | 
| boolean | updatable(Optional) Whether the column is included in
 SQL UPDATE statements generated by the persistence
 provider. | 
public abstract String name
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 or embeddable class; "_"; the name of the referenced primary key column. If there is no such referencing relationship property or field in the entity, or if the join is for an element collection, 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.
public abstract String referencedColumnName
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.  
 CollectionTable mapping, the
 referenced column is in the table of the entity containing the
 collection.
 Default (only applies if single join column is being used): The same name as the primary key column of the referenced table.
public abstract boolean unique
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.public abstract boolean nullable
public abstract boolean insertable
public abstract boolean updatable
public abstract String columnDefinition
Defaults to the generated SQL for the column.
public abstract String table
Default:
public abstract ForeignKey foreignKey
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