PrimaryKeyJoinColumn


1   /*
2    * The contents of this file are subject to the terms 
3    * of the Common Development and Distribution License 
4    * (the License).  You may not use this file except in
5    * compliance with the License.
6    * 
7    * You can obtain a copy of the license at 
8    * https://glassfish.dev.java.net/public/CDDLv1.0.html or
9    * glassfish/bootstrap/legal/CDDLv1.0.txt.
10   * See the License for the specific language governing 
11   * permissions and limitations under the License.
12   * 
13   * When distributing Covered Code, include this CDDL 
14   * Header Notice in each file and include the License file 
15   * at glassfish/bootstrap/legal/CDDLv1.0.txt.  
16   * If applicable, add the following below the CDDL Header, 
17   * with the fields enclosed by brackets [] replaced by
18   * you own identifying information: 
19   * "Portions Copyrighted [year] [name of copyright owner]"
20   * 
21   * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
22   */
23  package javax.persistence;
24  
25  import java.lang.annotation.Target  ;
26  import java.lang.annotation.Retention  ;
27  import static java.lang.annotation.ElementType.METHOD  ;
28  import static java.lang.annotation.ElementType.FIELD  ;
29  import static java.lang.annotation.ElementType.TYPE  ;
30  import static java.lang.annotation.RetentionPolicy.RUNTIME  ;
31  
32  /**
33   * This annotation specifies a primary key column that is used 
34   * as a foreign key to join to another table. 
35   *
36   * <p> It is used to join the primary table of an entity subclass 
37   * in the {@link InheritanceType#JOINED JOINED} mapping strategy 
38   * to the primary table of its superclass; it is used within a 
39   * {@link SecondaryTable} annotation to join a secondary table 
40   * to a primary table; and it may be used in a {@link OneToOne} 
41   * mapping in which the primary key of the referencing entity 
42   * is used as a foreign key to the referenced entity. 
43   *
44   * <p> If no <code>PrimaryKeyJoinColumn</code> annotation is 
45   * specified for a subclass in the {@link InheritanceType#JOINED 
46   * JOINED} mapping strategy, the foreign key columns are assumed 
47   * to have the same names as the primary key columns of the 
48   * primary table of the superclass
49   *
50   * <pre>
51   *
52   *    Example: Customer and ValuedCustomer subclass
53   *
54   *    &#064;Entity
55   *    &#064;Table(name="CUST")
56   *    &#064;Inheritance(strategy=JOINED)
57   *    &#064;DiscriminatorValue("CUST")
58   *    public class Customer { ... }
59   *    
60   *    &#064;Entity
61   *    &#064;Table(name="VCUST")
62   *    &#064;DiscriminatorValue("VCUST")
63   *    &#064;PrimaryKeyJoinColumn(name="CUST_ID")
64   *    public class ValuedCustomer extends Customer { ... }
65   * </pre>
66   *
67   * @since Java Persistence 1.0
68   */
69  @Target  ({TYPE, METHOD, FIELD})
70  @Retention  (RUNTIME)
71  
72  public @interface PrimaryKeyJoinColumn {
73  
74      /** 
75       * The name of the primary key column of the current table.
76       * <p> Defaults to the same name as the primary key column 
77       * of the primary table of the superclass ({@link 
78       * InheritanceType#JOINED JOINED} mapping strategy); the same 
79       * name as the primary key column of the primary table 
80       * ({@link SecondaryTable} mapping); or the same name as the 
81       * primary key column for the table for the referencing entity 
82       * ({@link OneToOne} mapping)
83       */
84      String   name() default "";
85  
86      /** 
87       * (Optional) The name of the primary key column of the table 
88       * being joined to.
89       * <p> Defaults to the same name as the primary key column 
90       * of the primary table of the superclass ({@link 
91       * InheritanceType#JOINED JOINED} mapping strategy); the same 
92       * name as the primary key column of the primary table 
93       * ({@link SecondaryTable} mapping); or the same name as the 
94       * primary key column for the table for the referencing entity 
95       * ({@link OneToOne} mapping)
96       */
97      String   referencedColumnName() default "";
98  
99      /**
100      * (Optional) The SQL fragment that is used when generating the 
101      * DDL for the column. This should not be specified for a 
102      * {@link OneToOne} primary key association.
103      * <p> Defaults to the generated SQL to create a column of the 
104      * inferred type.
105      */
106     String   columnDefinition() default "";
107 }
108
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