001/*
002 * Copyright (c) 2008, 2009, 2011 Oracle, Inc. All rights reserved.
003 *
004 * This program and the accompanying materials are made available under the
005 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
006 * which accompanies this distribution.  The Eclipse Public License is available
007 * at http://www.eclipse.org/legal/epl-v10.html and the Eclipse Distribution License
008 * is available at http://www.eclipse.org/org/documents/edl-v10.php.
009 */
010package javax.persistence;
011
012import java.lang.annotation.Retention;
013import java.lang.annotation.Target;
014
015import static java.lang.annotation.ElementType.FIELD;
016import static java.lang.annotation.RetentionPolicy.RUNTIME;
017
018/**
019 * Specifies a column that is used to maintain the persistent order of a list. The persistence provider is
020 * responsible for maintaining the order upon retrieval and in the database. The persistence provider is
021 * responsible for updating the ordering upon flushing to the database to reflect any insertion, deletion, or
022 * reordering affecting the list.
023 * <p>
024 * The <code>OrderColumn</code> annotation is specified on a OneToMany or ManyToMany relationship or on an
025 * element collection. The <code>OrderColumn</code> annotation is specified on the side of the relationship
026 * that references the collection that is to be ordered. The order column is not visible as part of the state
027 * of the entity or embeddable class.
028 * <p>
029 * The {@link OrderBy} annotation should be used for ordering that is visible as persistent state and
030 * maintained by the application. The <code>OrderBy</code> annotation is not used when
031 * <code>OrderColumn</code> is specified.
032 * <p>
033 * The order column must be of integral type. The persistence provider maintains a contiguous (non-sparse)
034 * ordering of the values of the order column when updating the association or element collection. The order
035 * column value for the first element is 0.
036 * <p>
037 * <pre>
038 *
039 *    Example:
040 *
041 *    &#064;Entity
042 *    public class CreditCard {
043 *
044 *       &#064;Id long ccNumber;
045 *
046 *       &#064;OneToMany  // unidirectional
047 *       &#064;OrderColumn
048 *       List&#060;CardTransaction&#062; transactionHistory;
049 *       ...
050 *    }
051 *
052 * </pre>
053 *
054 * @see OrderBy
055 * @since Java Persistence 2.0
056 */
057@Target({FIELD})
058@Retention(RUNTIME)
059public @interface OrderColumn {
060
061  /**
062   * (Optional) The name of the ordering column. Defaults to the concatenation of the name of the
063   * referencing property or field; "_"; "ORDER".
064   *
065   * @return name
066   */
067  String name() default "";
068
069  /**
070   * (Optional) Whether the database column is nullable.
071   *
072   * @return whether nullable
073   */
074  boolean nullable() default true;
075
076  /**
077   * (Optional) Whether the column is included in SQL INSERT statements generated by the persistence
078   * provider.
079   *
080   * @return whether insertable
081   */
082  boolean insertable() default true;
083
084  /**
085   * (Optional) Whether the column is included in SQL UPDATE statements generated by the persistence
086   * provider.
087   *
088   * @return whether updateable
089   */
090  boolean updatable() default true;
091
092  /**
093   * (Optional) The SQL fragment that is used when generating the DDL for the column. Defaults to generated
094   * SQL to create a column of the inferred type.
095   *
096   * @return column definition
097   */
098  String columnDefinition() default "";
099}