Java Reference
In-Depth Information
public class Student implements Serializable {
New annotations
JPA 2.1 added an annotation ( @Index ) to create indexes on tables when a schema
is generated from entities and an annotation ( @ForeignKey ) to designate foreign
keys of a table.
The @Index annotation has one mandatory parameter ( columnList ) to list the
columns that make up the index with different sort orders. It also has two optional
parameters: the name parameter, which allows you to change the default name of
the index, and the unique parameter to set the index as unique or not unique.
In parallel, @Index annotation was added as a part of Table , SecondaryTable ,
CollectionTable , JoinTable , and TableGenerator annotations.
The @ForeignKey can be used as element of JoinColumn , JoinColumns ,
MapKeyJoinColumn , MapKeyJoinColumns , PrimaryKeyJoinColumn ,
PrimaryKeyJoinColumns , CollectionTable , JoinTable , SecondaryT-
able , and AssociationOverride annotations to either define or modify the for-
eign key constraints on a table. It takes three parameters: name, value for the con-
straint, and the definition of the foreign key. The three parameters are optional.
An example of an entity with a foreign key and indexed columns is shown in the fol-
lowing code:
@Table(indexes = @Index(columnList = "name ASC,
id DESC"))
public class MyEntity implements Serializable {
private Long id;
private String name;
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